Compound, resin, and purification method thereof, material for forming underlayer film for lithography, composition for forming underlayer film, and underlayer film, as well as resist pattern forming method and circuit pattern forming method

ABSTRACT

The present invention provides a compound represented by following formula (1), 
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a 2n-valent group having 1 to 30 carbon atoms, each of R 2  to R 5  independently represents a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a halogen atom, a thiol group or a hydroxyl group, provided that at least one selected from R 1  to R 5  represents a group including an iodine atom and at least one R 4  and/or at least one R 5  represent/represents one or more selected from the group consisting of a hydroxyl group and a thiol group, each of m 2  and m 3  independently represents an integer of 0 to 8, each of m 4  and m 5  independently represents an integer of 0 to 9, provided that m 4  and m 5  do not represent 0 at the same time, n represents an integer of 1 to 4, and each of p 2  to p 5  independently represents an integer of 0 to 2.

TECHNICAL FIELD

The present invention relates to a compound, a resin, and a purificationmethod thereof, a material for forming an underlayer film forlithography, a composition for forming an underlayer film, and anunderlayer film, as well as a resist pattern forming method and acircuit pattern forming method.

BACKGROUND ART

Semiconductor devices are manufactured through microfabrication bylithography using a photoresist material, but are required to be madefiner by a pattern rule in accordance with the increase in integrationdegree and the increase in speed of LSI in recent years. In lithographyusing exposure to light, which is currently used as a general-purposetechnique, the resolution is now approaching the intrinsic limitationassociated with the wavelength of the light source.

A light source for lithography, for use in forming a resist pattern, hasa shorter wavelength from a KrF excimer laser (248 nm) to an ArF excimerlaser (193 nm). However, if the resist pattern is made finer and finer,there arises a problem of resolution or a problem of collapse of theresist pattern after development, and therefore there is demanded formaking a resist film thinner. Meanwhile, if the resist film is merelymade thinner, it is difficult to achieve the resist pattern having afilm thickness sufficient for processing a substrate. Accordingly, thereis increasingly required a process in which not only the resist patternbut also a resist underlayer film is prepared between a resist and asemiconductor substrate to be processed and the resist underlayer filmis allowed to have a function as a mask at the time of processing thesubstrate.

Currently, as the resist underlayer film for such a process, variousones are known. For example, as one which realizes a resist underlayerfilm for lithography, having a selection ratio of dry etching rate closeto the resist, unlike a conventional resist underlayer film having ahigh etching rate, there has been proposed a material for forming anunderlayer film for multilayer resist process, containing a resincomponent having at least a substituent which releases a terminal groupto form a sulfonic acid residue when a predetermined energy is applied,and a solvent (see, for example, Patent Literature 1). In addition, asone which realizes a resist underlayer film for lithography, having asmaller selection ratio of dry etching rate than the resist, there hasbeen proposed a resist underlayer film material including a polymerhaving a specified repeating unit (see, for example, Patent Literature2). Furthermore, as one which realizes a resist underlayer film forlithography, having a smaller selection ratio of dry etching rate thanthe semiconductor substrate, there has been proposed a resist underlayerfilm material including a polymer formed by co-polymerizing a repeatingunit of acenaphthylene, and a substituted or non-substituted repeatingunit having a hydroxy group (see, for example, Patent Literature 3).

On the other hand, as a material for allowing such a resist underlayerfilm to have a high etching resistance, an amorphous carbon underlayerfilm is well known, which is formed by CVD using methane gas, ethanegas, acetylene gas, or the like as a raw material. However, there isdemanded, in terms of process, a resist underlayer film material thatcan form a resist underlayer film in a wet process such as a spincoating method or screen printing.

In addition, as a material that is excellent in optical characteristicsand etching resistance and that is capable of being dissolved in asolvent and being applied to a wet process, there has been proposed acomposition for forming an underlayer film for lithography, whichcontains a naphthalene formaldehyde polymer including a specifiedconstituent unit, and an organic solvent (see, for example, PatentLiteratures 4 and 5).

Meanwhile, with respect to a forming method of an intermediate layer foruse in forming a resist underlayer film in a three-layer process, forexample, known are a forming method of a silicon nitride film (see, forexample, Patent Literature 6), and a CVD forming method of a siliconnitride film (see, for example, Patent Literature 7). In addition, as anintermediate layer material for a three-layer process, known is amaterial containing a silsesquioxane-based silicon compound (see, forexample, Patent Literatures 8 and 9).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Laid-Open No. 2004-177668

Patent Literature 2: Japanese Patent Laid-Open No. 2004-271838

Patent Literature 3: Japanese Patent Laid-Open No. 2005-250434

Patent Literature 4: International Publication No. WO 2009/072465

Patent Literature 5: International Publication No. WO 2011/034062

Patent Literature 6: Japanese Patent Laid-Open No. 2002-334869

Patent Literature 7: International Publication No. WO 2004/066377

Patent Literature 8: Japanese Patent Laid-Open No. 2007-226170

Patent Literature 9: Japanese Patent Laid-Open No. 2007-226204

SUMMARY OF INVENTION Technical Problem

As described above, many materials for forming an underlayer film forlithography have been conventionally proposed, but there are no onesthat not only have such a high solvent solubility as to be able to beapplied to a wet process such as a spin coating method or screenprinting, but also simultaneously satisfy heat resistance and etchingresistance at a high level, and thus a new material is required to bedeveloped.

The present invention has been then made in view of the above problem ofthe prior art, and an object thereof is to provide a compound which canbe applied to a wet process, and which is useful for forming aphotoresist underlayer film excellent in heat resistance and etchingresistance.

Solution to Problem

The present inventors have intensively studied to solve the aboveproblem of the prior art, and as a result, have found that a photoresistunderlayer film excellent in heat resistance and etching resistance isobtained by using a compound having a specified structure, therebyleading to the completion of the present invention. That is, the presentinvention is as follows.

[1]

A compound represented by following formula (1),

wherein R¹ represents a 2n-valent group having 1 to 30 carbon atoms,each of R² to R⁵ independently represents a straight, branched or cyclicalkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxygroup having 1 to 30 carbon atoms, a halogen atom, a thiol group or ahydroxyl group, provided that at least one selected from R¹ to R⁵represents a group including an iodine atom and at least one R⁴ and/orat least one R⁵ represent/represents one or more selected from the groupconsisting of a hydroxyl group and a thiol group, each of m² and m³independently represents an integer of 0 to 8, each of m⁴ and m⁵independently represents an integer of 0 to 9, provided that m⁴ and m⁵do not represent 0 at the same time, n represents an integer of 1 to 4,and each of p² to p⁵ independently represents an integer of 0 to 2.[2]

The compound according to [1], wherein, in the formula (1), at least oneR² and/or at least one R³ represent/represents one or more selected fromthe group consisting of a hydroxyl group and a thiol group.

[3]

The compound according to [1] or [2], wherein the compound representedby the formula (1) is a compound represented by following formula (1a),

wherein R¹ to R⁵ and n are the same as defined in the formula (1), eachof m^(2′) and m^(3′) independently represents an integer of 0 to 4, andeach of m^(4′) and m^(5′) independently represents an integer of 0 to 5,provided that m^(4′) and m^(5′) do not represent 0 at the same time.[4]

The compound according to [3], wherein the compound represented by theformula (1a) is a compound represented by following formula (1b),

wherein R¹ is the same as defined in the formula (1), each of R⁶ and R⁷independently represents a straight, branched or cyclic alkyl grouphaving 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms,an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1to 30 carbon atoms, a halogen atom or a thiol group, provided that atleast one selected from R¹, R⁶ and R⁷ represents a group including aniodine atom, and each of m⁶ and m⁷ independently represents an integerof 0 to 7. [5]

The compound according to [4], wherein the compound represented by theformula (1b) is a compound represented by following formula (1c),

wherein each R⁸ independently represents a hydrogen atom, a cyano group,a nitro group, a heterocyclic group, a halogen atom, a straightaliphatic hydrocarbon group having 1 to 20 carbon atoms, a branchedaliphatic hydrocarbon group having 3 to 20 carbon atoms, a cyclicaliphatic hydrocarbon group having 3 to 20 carbon atoms, an aryl grouphaving 6 to 20 carbon atoms, an alkenyl group having 2 to 10 carbonatoms, an alkoxy group having 1 to 30 carbon atoms, a thiol group or ahydroxyl group, provided that at least one R⁸ represents a groupincluding an iodine atom.[6]

The compound according to [5], wherein the compound represented by theformula (1c) is a compound represented by following formula (1d),

wherein each R⁹ independently represents a cyano group, a nitro group, aheterocyclic group, a halogen atom, a straight aliphatic hydrocarbongroup having 1 to 20 carbon atoms, a branched aliphatic hydrocarbongroup having 3 to 20 carbon atoms, a cyclic aliphatic hydrocarbon grouphaving 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms,an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1to 30 carbon atoms, a thiol group or a hydroxyl group, and m⁹ representsan integer of 0 to 4.[7]

A resin obtained with the compound according to any of [1] to [6] as amonomer.

[8]

The resin according to [7], wherein the resin is obtained by reactingthe compound with a compound having crosslinking reactivity.

[9]

The resin according to [8], wherein the compound having crosslinkingreactivity is an aldehyd, a ketone, a carboxylic acid, carboxylichalide, a halogen-containing compound, an amino compound, an iminocompound, an isocyanate or an unsaturated hydrocarbon group-containingcompound.

[10]

A resin having a following structure represented by formula (2),

wherein R¹ represents a 2n-valent group having 1 to 30 carbon atoms,each of R² to R⁵ independently represents a straight, branched or cyclicalkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxygroup having 1 to 30 carbon atoms, a halogen atom, a thiol group or ahydroxyl group, provided that at least one selected from R¹ to R⁵represents a group including an iodine atom and at least one R⁴ and/orat least one R⁵ represent/represents one or more selected from ahydroxyl group and a thiol group, L represents a straight or branchedalkylene group having 1 to 20 carbon atoms, or a single bond, each of m²and m³ independently represents an integer of 0 to 8, each of m⁴ and m⁵independently represents an integer of 0 to 9, provided that m⁴ and m⁵do not represent 0 at the same time, n represents an integer of 1 to 4,and each of p² to p⁵ independently represents an integer of 0 to 2.[11]

A material for forming an underlayer film for lithography, comprising atleast one selected from the group consisting of the compound accordingto any of [1] to [6] and the resin according to any of [7] to [10].

[12]

A composition for forming the underlayer film for lithography,comprising the material for forming the underlayer film for lithographyaccording to [11], and a solvent.

[13]

The composition for forming the underlayer film for lithographyaccording to [12], further comprising an acid generator.

[14]

The composition for forming the underlayer film for lithographyaccording to [12] or [13], further comprising a crosslinking agent.

[15]

An underlayer film for lithography, wherein the underlayer film isformed from the composition for forming the underlayer film forlithography according to any of [12] to [14]

[16]

A resist pattern forming method, comprising a step of forming anunderlayer film on a substrate by using the composition for forming theunderlayer film according to any of [12] to [14], a step of forming atleast one photoresist layer on the underlayer film, and a step ofirradiating a predetermined region of the photoresist layer withradiation, and developing it.

[17]

A circuit pattern forming method, comprising

a step of forming an underlayer film on a substrate by using thecomposition for forming the underlayer film according to any of [12] to[14],

a step of forming an intermediate layer film on the underlayer film byusing a silicon atom-containing resist intermediate layer film material,

a step of forming at least one photoresist layer on the intermediatelayer film,

a step of irradiating a predetermined region of the photoresist layerwith radiation, to form a developed resist pattern,

a step of etching the intermediate layer film with the resist pattern asa mask, to form an intermediate layer film pattern,

a step of etching the underlayer film with the intermediate layer filmpattern as an etching mask, to form an underlayer film pattern, and

a step of etching the substrate with the underlayer film pattern as anetching mask, to form a substrate pattern.

[18]

A purification method of a compound or a resin, comprising a step ofbringing a solution including the compound according to any of [1] to[6] or the resin according to any of [7] to [10], and an organic solventoptionally immiscible with water into contact with an acidic aqueoussolution, to thereby extract the compound or the resin.

[19]

The purification method according to [18], wherein the acidic aqueoussolution is an aqueous solution of at least one mineral acid selectedfrom the group consisting of hydrochloric acid, sulfuric acid, nitricacid and phosphoric acid, or an aqueous solution of at least one organicacid selected from the group consisting of acetic acid, propionic acid,oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid,tartaric acid, citric acid, methanesulfonic acid, phenolsulfonic acid,p-toluenesulfonic acid and trifluoroacetic acid.

[20]

The purification method according to [18] or [19], wherein the organicsolvent optionally immiscible with water is toluene, 2-heptanone,cyclohexanone, cyclopentanone, methyl isobutyl ketone, propylene glycolmonomethyl ether acetate or ethyl acetate.

[21]

The purification method according to any of [18] to [20], furthercomprising a step of extracting the compound or the resin with water,after the extraction step.

Advantageous Effect of Invention

The compound according to the present invention can realize a materialfor forming an underlayer film for lithography, which can be applied toa wet process and which is useful for forming a photoresist underlayerfilm excellent in heat resistance and etching resistance.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment (hereinafter, simply referred to as “thepresent embodiment”.) of the present invention will be described. It isto be noted that the following present embodiments are illustrative fordescribing the present invention, and the present invention is notlimited only to the present embodiments.

[Compound]

A compound of the present embodiment is represented by the followingformula (1). The compound of the present embodiment has such aconfiguration, and therefore is high in heat resistance and also high insolvent solubility.

(in formula (1), R¹ represents a 2n-valent group having 1 to 30 carbonatoms, each of R² to R⁵ independently represents a straight, branched orcyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, analkoxy group having 1 to 30 carbon atoms, a halogen atom, a thiol groupor a hydroxyl group, provided that at least one selected from R¹ to R⁵represents a group including an iodine atom and at least one R⁴ and/orat least one R⁵ represent/represents one or more selected from the groupconsisting of a hydroxyl group and a thiol group, each of m2 and m3independently represents an integer of 0 to 8, each of m⁴ and m⁵independently represents an integer of 0 to 9, provided that m⁴ and m⁵do not represent 0 at the same time, n represents an integer of 1 to 4,and each of p² to p⁵ independently represents an integer of 0 to 2.)

In the formula (1), R¹ represents a 2n-valent group having 1 to 30carbon atoms, and respective aromatic rings are bonded to each other viaR¹. The “2n-valent group” means an alkylene group having 1 to 30 carbonatoms when n=1, an alkanetetrayl group having 1 to 30 carbon atoms whenn=2, an alkanehexayl group having 2 to 30 carbon atoms when n=3, and analkaneoctayl group having 3 to 30 carbon atoms when n=4. Examples of the2n-valent group include, but are not particularly limited, those havinga straight hydrocarbon group, a branched hydrocarbon group, and analicyclic hydrocarbon group. Herein, the alicyclic hydrocarbon groupalso includes a bridged alicyclic hydrocarbon group. The 2n-valent groupmay also have a double bond, a hetero atom, or an aromatic group having6 to 30 carbon atoms. Furthermore, the aromatic group may also have acyano group, a nitro group, a heterocyclic group, a halogen atom, astraight aliphatic hydrocarbon group having 1 to 20 carbon atoms, abranched aliphatic hydrocarbon group having 3 to 20 carbon atoms, acyclic aliphatic hydrocarbon group having 3 to 20 carbon atoms, an arylgroup having 6 to 20 carbon atoms, an alkenyl group having 2 to 10carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a thiol groupor a hydroxyl group.

In the formula (1), each of R² to R⁵ independently represents amonovalent group that is a straight, branched or cyclic alkyl grouphaving 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms,an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1to 30 carbon atoms, a halogen atom, a thiol group or a hydroxyl group,provided that at least one selected from R¹ to R⁵ represents a groupincluding an iodine atom and at least one R⁴ and/or at least one R⁵represents one or more selected from the group consisting of a hydroxylgroup and a thiol group. In the present specification, the “at least oneselected from R¹ to R⁵” means “at least one group selected from R¹ toR⁵”, and does not mean “at least one group selected from R¹ to R⁵”.

In the formula (1), each of m² and m³ independently represents aninteger of 0 to 8, each of m⁴ and m⁵ independently represents an integerof 0 to 9, provided that m⁴ and m⁵ do not represent 0 at the same time,n represents an integer of 1 to 4, and each of p² to p⁵ independentlyrepresents an integer of 0 to 2.

The group including an iodine atom is not particularly limited withrespect to R¹, and examples thereof include respective groups having astraight hydrocarbon group having 1 to 30 carbon atoms, substituted withan iodine atom, a branched hydrocarbon group having 3 to 30 carbonatoms, substituted with an iodine atom, an alicyclic hydrocarbon grouphaving 3 to 30 carbon atoms, substituted with an iodine atom, and anaromatic group having 6 to 30 carbon atoms, substituted with an iodineatom. Respective groups having a branched hydrocarbon group having 3 to30 carbon atoms, substituted with an iodine atom, an alicyclichydrocarbon group having 3 to 30 carbon atoms, substituted with aniodine atom, and an aromatic group having 6 to 30 carbon atoms,substituted with an iodine atom are preferable, respective groups havingan alicyclic hydrocarbon group having 3 to 30 carbon atoms, substitutedwith an iodine atom, and an aromatic group having 6 to 30 carbon atoms,substituted with an iodine atom are more preferable, and a group havingan aromatic group having 6 to 30 carbon atoms, substituted with aniodine atom is further preferable, in terms of heat resistance.

The group including an iodine atom is not particularly limited withrespect to R² to R⁵, and examples thereof include an iodine atom, astraight aliphatic hydrocarbon group having 1 to 6 carbon atoms,substituted with an iodine atom, a branched aliphatic hydrocarbon grouphaving 3 to 6 carbon atoms, substituted with an iodine atom, a cyclicaliphatic hydrocarbon group having 3 to 6 carbon atoms, substituted withan iodine atom, and an aryl group having 6 carbon atoms, substitutedwith an iodine atom. The group including an iodine atom is preferably aniodine atom, a straight aliphatic hydrocarbon group having 1 to 6 carbonatoms, substituted with an iodine atom, and a branched aliphatichydrocarbon group having 3 to 6 carbon atoms, substituted with an iodineatom, more preferably an iodine atom, and a straight aliphatichydrocarbon group having 1 to 6 carbon atoms, substituted with an iodineatom, and further preferably an iodine atom, in terms of solubility in asafety solvent, or the like.

The compound represented by the formula (1) has a high heat resistancedue to rigidity of its structure while having a relatively low molecularweight, and therefore it can be used even under a high-temperaturebaking condition. In addition, the compound has a relatively lowmolecular weight and a low viscosity, and therefore, even when beingapplied to a substrate having a step (in particular, fine space, holepattern and the like), it can be easily filled uniformly in every partof the step, and as a result, a material for forming an underlayer filmfor lithography using such a compound can be improved in terms ofembedding properties in a relatively advantageous manner. In addition,flatness of a film to be formed is also excellent. Furthermore, a highetching resistance is also imparted.

In the formula (1), at least one R² and/or at least one R³ preferablyrepresent/represents one or more selected from the group consisting of ahydroxyl group and a thiol group in terms of ease of crosslinking,further solubility in an organic solvent, and a decrease in defects.

The compound represented by the formula (1) is more preferably acompound represented by the following formula (1a) in terms of feedingproperty of raw materials.

In formula (1a), R¹ to R⁵ and n are the same as defined in the formula(1), each of m2′ and m^(3′) independently represents an integer of 0 to4, and each of m^(4′) and m^(5′) independently represents an integer of0 to 5, provided that m^(4′) and m5′ do not represent 0 at the sametime.

The compound represented by the formula (1a) is further preferably acompound represented by the following formula (1b) in terms ofsolubility in an organic solvent.

In formula (1b), R¹ is the same as defined in the formula (1), each ofR⁶ and R⁷ independently represents a straight, branched or cyclic alkylgroup having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbonatoms, an alkenyl group having 2 to 10 carbon atoms, a halogen atom or athiol group, provided that at least one selected from R¹, R⁶ and R⁷represents a group including an iodine atom, and each of m⁶ and m⁷independently represents an integer of 0 to 7. In the presentspecification, the “at least one selected from R¹, R⁶ and R⁷” means “atleast one group selected from R¹, R⁶ and R⁷”, and does not mean “atleast one group selected from R¹, R⁶ and R⁷”.

The compound represented by the formula (1b) is more further preferablya compound represented by the following formula (1c) in terms of furthersolubility in an organic solvent.

In formula (1c), each R⁸ independently represents a hydrogen atom, acyano group, a nitro group, a heterocyclic group, a halogen atom, astraight aliphatic hydrocarbon group having 1 to 20 carbon atoms, abranched aliphatic hydrocarbon group having 3 to 20 carbon atoms, acyclic aliphatic hydrocarbon group having 3 to 20 carbon atoms, an arylgroup having 6 to 20 carbon atoms, an alkenyl group having 2 to 10carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a thiol groupor a hydroxyl group, provided that at least one R⁸ represents a groupincluding an iodine atom, in terms of quality stabilization.

The compound represented by the formula (1c) is still more preferably acompound represented by the following formula (1d) in terms of ease ofcrosslinking, further solubility in an organic solvent, and a decreasein defects.

In formula (1d), each R⁹ independently represents a cyano group, a nitrogroup, a heterocyclic group, a halogen atom, a straight aliphatichydrocarbon group having 1 to 20 carbon atoms, a branched aliphatichydrocarbon group having 3 to 20 carbon atoms, a cyclic aliphatichydrocarbon group having 3 to 20 carbon atoms, an aryl group having 6 to20 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxygroup having 1 to 30 carbon atoms, a thiol group or a hydroxyl group,and m⁹ represents an integer of 0 to 4.

Hereinafter, specific examples of the compound represented by theformula (1) are illustrated, but the compound represented by the formula(1) is not limited to specific examples recited herein.

In specific examples of the compound represented by the formula (1), R²to R⁵ and m² to m⁵ are the same as defined in the formula (1).

In specific examples of the compound represented by the formula (1), R²to R⁵ are the same as defined in the formula (1), each of m^(2′) andm^(3′) independently represents an integer of 0 to 4, and each of m^(4′)and m^(5′) independently represents an integer of 0 to 5, provided thatm^(4′) and m^(5′) do not represent 0 at the same time.

In specific examples of the compound represented by the formula (1), R²to R⁵ and m2 to m5 are the same as defined in the formula (1).

In specific examples of the compound represented by the formula (1), R²to R⁵ are the same as defined in the formula (1), each of m^(2′) andm^(3′) independently represents an integer of 0 to 4, and each of m^(4′)and m^(5′) independently represents an integer of 0 to 5, provided thatm^(4′) and m^(5′) do not represent 0 at the same time.

The compound represented by the formula (1) of the present embodimentcan be appropriately synthesized by applying a known method, and asynthesis method thereof is not particularly limited. For example, oneor more compounds selected from the group consisting of biphenols,bithiophenols, binaphthols, bithionaphthols and bianthracenol (A1), andone or more compounds selected from the group consisting of aldehydes(A2) and ketones (A3) can be subjected to a polycondensation reactionunder ordinary pressure in the presence of an acid catalyst to therebyprovide the above compound. The reaction can also be performed underpressure, if necessary.

Examples of the biphenols include biphenol, methyl biphenol and methoxybinaphthol, but are not particularly limited thereto. These can be usedsingly or in combinations of two or more thereof. Among them, biphenolis preferably used in terms of stable feeding property of raw materials.

Examples of the bithiophenols include bithiophenol, methyl bithiophenoland methoxy bithiophenol, but are not particularly limited thereto.These can be used singly or in combinations of two or more thereof.Among them, bithiophenol is preferably used in terms of stable feedingproperty of raw materials.

Examples of the binaphthols include binaphthol, methyl binaphthol andmethoxy binaphthol, but are not particularly limited thereto. These canbe used singly or in combinations of two or more thereof. Among them,binaphthol is preferably used in terms of increasing the carbon atomconcentration and enhancing heat resistance.

Examples of the bithionaphthols include bithionaphthol, methylbithionaphthol and methoxy bithionaphthol, but are not particularlylimited thereto. These can be used singly or in combinations of two ormore thereof. Among them, bithionaphthol is preferably used in terms ofincreasing the carbon atom concentration and enhancing heat resistance.

Examples of the bianthracenols include bianthracenol, methylbianthracenol and methoxy bianthracenol, but are not particularlylimited thereto. These can be used singly or in combinations of two ormore thereof. Among them, bianthracenol is more preferably used in termsof an increase in the carbon atom concentration and an enhancement inheat resistance.

The compound suitable as the aldehydes is a compound having 2 to 59carbon atoms, having 1 to 4 formyl groups and a group including aniodine atom, and is selected from an aromatic aldehyde compound and analiphatic aldehyde compound. The aromatic aldehyde compound ispreferably an aldehyde compound having 7 to 24 carbon atoms, andexamples thereof include iodobenzaldehyde, methyliodobenzaldehyde,dimethyliodobenzaldehyde, ethyliodobenzaldehyde, propyliodobenzaldehyde,butyliodobenzaldehyde, ethylmethyliodobenzaldehyde,isopropylmethyliodobenzaldehyde, diethyliodobenzaldehyde,methoxyiodobenzaldehyde, iodonaphthaldehyde, iodoanthraldehyde,cyclopropyliodobenzaldehyde, cyclobutyliodobenzaldehyde,cyclopentyliodobenzaldehyde, cyclohexyliodobenzaldehyde,phenyliodobenzaldehyde, naphthyliodobenzaldehyde,adamantyliodobenzaldehyde, norbornyliodobenzaldehyde,lactyliodobenzaldehyde, isopropyliodobenzaldehyde,normaliodobenzaldehyde, bromoiodobenzaldehyde,dimethylaminoiodobenzaldehyde, hydroxyiodobenzaldehyde,dihydroxyiodobenzaldehyde and trihydroxyiodobenzaldehyde, morepreferable are iodobenzaldehyde, methyliodobenzaldehyde,dimethyliodobenzaldehyde and ethyliodobenzaldehyde, and furtherpreferable is iodobenzaldehyde. The aromatic aldehyde compound may alsohave a straight or branched alkyl group having 1 to 4 carbon atoms, acyano group, a hydroxyl group, halogen, and the like as long as theeffect of the present invention is not impaired. The aromatic aldehydecompound may be used singly or in combinations of two or more thereof.

The aliphatic aldehyde compound is preferably a compound having 3 to 24carbon atoms, and examples of the compound having 3 to 24 carbon atomsinclude iodopropanal, iodoisopropanal, iodobutanal, iodoisobutanal,iodo-t-butanal, iodopentanal, iodoisopentanal, iodoneopentanal,iodohexanal, iodoisohexanal, iodooctanal, iododecanal, iodododecanal,iodoundecenal, iodocyclopropanecarboxyaldehyde,iodocyclobutanecarboxyaldehyde and iodocyclohexanecarboxyaldehyde, morepreferable are iodoisobutanal, iodo-t-butanal, iodopentanal,iodoisopentanal, iodoneopentanal, iodohexanal, iodoisohexanal,iodooctanal, iododecanal, iodododecanal, iodoundecenal,iodocyclopropanecarboxyaldehyde, iodocyclobutanecarboxyaldehyde andiodocyclohexanecarboxyaldehyde, and further preferable are iodooctanal,iododecanal, iodododecanal and iodocyclohexanecarboxyaldehyde. Thealiphatic aldehyde compound may also have a straight or branched alkylgroup having 1 to 4 carbon atoms, a cyano group, a hydroxyl group, ahalogen atom, and the like as long as the effect of the presentinvention is not impaired. The aliphatic aldehyde compound may be usedsingly or in combinations of two or more thereof.

The compound suitable as the ketones is a compound having 2 to 59 carbonatoms, having 1 to 2 carbonyl groups and a group including an iodineatom, and is preferably ketones having 7 to 24 carbon atoms, andexamples thereof include iodobenzophenone, methyliodobenzophenone,dimethyliodobenzophenone, ethyliodobenzophenone, propyliodobenzophenone,butyliodobenzophenone, ethylmethyliodobenzophenone,isopropylmethyliodobenzophenone, diethyliodobenzophenone,methoxyiodobenzophenone, iodophenyl methyl ketone and methyliodophenylmethyl ketone, and preferable are iodobenzophenone and iodophenyl methylketone. The ketones may also have a straight or branched alkyl grouphaving 1 to 4 carbon atoms, a cyano group, a hydroxyl group, halogen,and the like as long as the effect of the present invention is notimpaired. The ketones may be used singly or in combinations of two ormore thereof.

The acid catalyst for use in the above reaction can be appropriatelyselected from known ones and used, and is not particularly limited. Suchan acid catalyst is an inorganic acid or an organic acid, as widelyknown, and examples thereof include inorganic acids such as hydrochloricacid, sulfuric acid, phosphoric acid, hydrobromic acid, or hydrofluoricacid; organic acids such as oxalic acid, malonic acid, succinic acid,adipic acid, sebacic acid, citric acid, fumaric acid, maleic acid,formic acid, p-toluenesulfonic acid, methanesulfonic acid,trifluoroacetic acid, dichloroacetic acid, trichloroacetic acid,trifluoromethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonicacid, or naphthalenedisulfonic acid; Lewis acids such as zinc chloride,aluminum chloride, iron chloride, or boron trifluoride; or solid acidssuch as tungstosilicic acid, tungstophosphoric acid, silicomolybdicacid, or phosphomolybdic acid, but are not particularly limited thereto.Among them, organic acids and solid acids are preferable in terms ofproduction, and hydrochloric acid or sulfuric acid is more preferably interms of production such as availability or handleability. Herein, theseacid catalysts can be used alone, or two or more thereof can be used incombination. In addition, the amount of the acid catalyst to be used canbe appropriately set depending on the types of raw materials to be usedand the catalyst to be used, reaction conditions, and the like, and isnot particularly limited, but the amount is preferably 0.01 to 100 partsby mass based on 100 parts by mass of reaction raw materials.

A reaction solvent may also be used during the above reaction. Thereaction solvent that can be used is not particularly limited and isappropriately selected from known ones, as long as the reaction of thealdehydes or ketones to be used and the biphenols, bithiophenols,binaphthols, bithionaphthols or bianthracene diols to be usedprogresses. Examples thereof include ethyl acetate, propyl acetate,butyl acetate, 4-butyrolactone, ethylene glycol, propylene glycol,methanol, ethanol, propanol, butanol, tetrahydrofuran, dioxane, ethyleneglycol dimethyl ether, ethylene glycol diethyl ether, propylene glycolmonomethyl ether, propylene glycol monoethyl ether, propylene glycolmonomethyl ether acetate, and a mixed solvent thereof. Herein, thesesolvents can be used alone, or two or more thereof can be used incombination.

In addition, the amount of the solvent to be used can be appropriatelyset depending on the types of raw materials to be used and the catalystto be used, reaction conditions, and the like, and is not particularlylimited, but the amount is preferably 0 to 2000 parts by mass based on100 parts by mass of reaction raw materials. Furthermore, the reactiontemperature in the above reaction can be appropriately selecteddepending on the reactivity of reaction raw materials, and is notparticularly limited, but the reaction temperature preferably rangesfrom 10 to 200° C.

In order to obtain the compound represented by the formula (1) of thepresent embodiment, the reaction temperature is preferably high and,specifically, preferably ranges from 60 to 200° C. Herein, the reactionmethod that can be used is appropriately selected from known methods,and is not particularly limited, but includes a method in which thebiphenols, bithiophenols, binaphthols, bithionaphthols or bianthracenediols, the aldehydes or ketones, and the catalyst are charged at once,and a method in which the biphenols, bithiophenols, binaphthols,bithionaphthols or bianthracene diols, and the aldehydes or ketones aredropped in the presence of the catalyst. After completion of thepolycondensation reaction, the resulting compound can be isolatedaccording to an ordinary method, and the isolation method is notparticularly limited. For example, in order to remove the unreacted rawmaterials and the catalyst present in the system, a common method inwhich the temperature in a reaction tank is raised to 130 to 230° C. toremove a volatile content at about 1 to 50 mmHg can be adopted tothereby provide an objective compound.

The reaction progresses under a preferable reaction condition in which 1mol to an excess amount of the biphenols, bithiophenols, binaphthols,bithionaphthols or bianthracene diols and 0.001 to 1 mol of the acidcatalyst are used based on 1 mol of the aldehydes or ketones at ordinarypressure and at 50 to 150° C. for about 20 minutes to 100 hours.

After completion of the reaction, the objective compound can be isolatedby a known method. For example, the objective compound, the compoundrepresented by the formula (1), can be obtained by concentrating areaction liquid, adding pure water thereto to precipitate a reactionproduct, cooling the resultant to room temperature followed byfiltration for separation, drying a solid obtained by filtration, thenseparating the solid into the reaction product and a by-product forpurification by column chromatography, and performing distilling off ofthe solvent, filtration and drying.

[Resin]

A resin of the present embodiment is a resin obtained with the compoundrepresented by the formula (1) as a monomer. Specific examples of theresin include a resin having a structure represented by formula (2).

In formula (2), R¹ represents a 2n-valent group having 1 to 30 carbonatoms, each of R² to R⁵ independently represents a straight, branched orcyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, analkoxy group having 1 to 30 carbon atoms, a halogen atom, a thiol groupor a hydroxyl group, provided that at least one selected from R¹ to R⁵represents a group including an iodine atom and at least one R⁴ and/orat least one R⁵ represent/represents one or more selected from the groupconsisting of a hydroxyl group and a thiol group, L represents astraight or branched alkylene group having 1 to 20 carbon atoms, or asingle bond, each of m² and m³ independently represents an integer of 0to 8, each of m⁴ and m⁵ independently represents an integer of 0 to 9,provided that m⁴ and m⁵ do not represent 0 at the same time, nrepresents an integer of 1 to 4, and each of p² to p⁵ independentlyrepresents an integer of 0 to 2.

In addition, the resin of the present embodiment is obtained by reactingthe compound represented by the formula (1) with a compound havingcrosslinking reactivity.

As the compound having crosslinking reactivity, known one can be usedwithout any particular limitation as long as it can provide an oligomeror a polymer of the compound represented by the formula (1). Specificexamples thereof include an aldehyde, a ketone, a carboxylic acid, acarboxylic halide, a halogen-containing compound, an amino compound, animino compound, an isocyanate, and an unsaturated hydrocarbongroup-containing compound, but are not particularly limited thereto. Inaddition, the compound having crosslinking reactivity is preferably analdehyde, a ketone, a carboxylic acid, a carboxylic halide, ahalogen-containing compound, an amino compound, an imino compound, anisocyanate or an unsaturated hydrocarbon group-containing compound.

Specific examples of the resin of the present embodiment include anovolac resin obtained by a condensation reaction of the compoundrepresented by the formula (1) with an aldehyde as the compound havingcrosslinking reactivity, or the like.

Herein, examples of the aldehyde for use in forming the novolac resin ofthe compound represented by the formula (1) include formaldehyde,trioxane, paraformaldehyde, benzaldehyde, acetaldehyde, propylaldehyde,phenylacetaldehyde, phenylpropylaldehyde, hydroxybenzaldehyde,chlorobenzaldehyde, nitrobenzaldehyde, methylbenzaldehyde,ethylbenzaldehyde, butylbenzaldehyde, biphenylaldehyde, naphthaldehyde,anthracenecarbaldehyde, phenanthrenecarbaldehyde, pyrenecarbaldehyde,and furfural, but are not particularly limited thereto. Among them,formaldehyde is preferable. Herein, these aldehydes can be used alone,or two or more thereof can be used in combination. In addition, theamount of the aldehydes to be used is not particularly limited, but theamount is preferably 0.2 to 5 mol and more preferably 0.5 to 2 mol basedon 1 mol of the compound represented by the formula (1).

A catalyst can also be used in the condensation reaction of the compoundrepresented by the formula (1) with an aldehyde. The acid catalyst thatcan be here used is appropriately selected from known ones, and is notparticularly limited. Such an acid catalyst is an inorganic acid or anorganic acid, as widely known, and examples thereof include inorganicacids such as hydrochloric acid, sulfuric acid, phosphoric acid,hydrobromic acid, or hydrofluoric acid; organic acids such as oxalicacid, malonic acid, succinic acid, adipic acid, sebacic acid, citricacid, fumaric acid, maleic acid, formic acid, p-toluenesulfonic acid,methanesulfonic acid, trifluoroacetic acid, dichloroacetic acid,trichloroacetic acid, trifluoromethanesulfonic acid, benzenesulfonicacid, naphthalenesulfonic acid, or naphthalenedisulfonic acid; Lewisacids such as zinc chloride, aluminum chloride, iron chloride, or borontrifluoride; or solid acids such as tungstosilicic acid,tungstophosphoric acid, silicomolybdic acid, or phosphomolybdic acid,but are not particularly limited thereto. Among them, organic acids andsolid acids are preferable in terms of production, and hydrochloric acidand sulfuric acid are more preferably used in terms of production suchas availability or handleability. Herein, these acid catalysts can beused alone, or two or more thereof can be used in combination. Inaddition, the amount of the acid catalyst to be used can beappropriately set depending on the types of raw materials to be used andthe catalyst to be used, reaction conditions, and the like, and is notparticularly limited, but the amount is preferably 0.01 to 100 parts bymass based on 100 parts by mass of reaction raw materials. In thisregard, in the case of copolymerization with a compound having anon-conjugated double bond, such as indene, hydroxyindene, benzofuran,hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, trisphenol,dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene,5-vinylnorborna-2-ene, α-pinene, β-pinene, and limonene, aldehydes arenot necessarily needed.

A reaction solvent can also be used in the condensation reaction of thecompound represented by the formula (1) with an aldehyde. The reactionsolvent in the polycondensation, which can be used, is appropriatelyselected from known ones, and is not particularly limited, but examplesthereof include water, methanol, ethanol, propanol, butanol,tetrahydrofuran, dioxane, and a mixed solvent thereof. Herein, thesesolvents can be used alone, or two or more thereof can be used incombination.

In addition, the amount of the solvent to be used can be appropriatelyset depending on the types of raw materials to be used and the catalystto be used, reaction conditions, and the like, and is not particularlylimited, but the amount preferably ranges from 0 to 2000 parts by massbased on 100 parts by mass of reaction raw materials. Furthermore, thereaction temperature can be appropriately selected depending on thereactivity of reaction raw materials, and is not particularly limited,but the reaction temperature usually ranges from 10 to 200° C. Herein,the reaction method that can be used is appropriately selected fromknown methods, and is not particularly limited, but includes a method inwhich the compound represented by the formula (1), the aldehydes, andthe catalyst are charged at once, and a method in which the compoundrepresented by the formula (1) and the aldehydes are dropped in thepresence of the catalyst.

After completion of the polycondensation reaction, the resultingcompound can be isolated according to an ordinary method, and theisolation method is not particularly limited. For example, in order toremove the unreacted raw materials and the catalyst present in thesystem, a common method in which the temperature in a reaction tank israised to 130 to 230° C. to remove a volatile content at about 1 to 50mmHg can be adopted to thereby provide an objective novolac resin.

Herein, the resin of the present embodiment may be a homopolymer of thecompound represented by the formula (1), or may be a copolymer thereofwith other phenols. Examples of the copolymerizable phenols includephenol, cresol, dimethylphenol, trimethylphenol, butylphenol,phenylphenol, diphenylphenol, naphthylphenol, resorcinol,methylresorcinol, catechol, butylcatechol, methoxyphenol, methoxyphenol,propylphenol, pyrogallol, and thymol, but are not particularly limitedthereto.

In addition, the resin of the present embodiment may be one obtained bycopolymerization with a polymerizable monomer other than theabove-described other phenols. Examples of such a copolymerizablemonomer include naphthol, methylnaphthol, methoxynaphthol,dihydroxynaphthalene, indene, hydroxyindene, benzofuran,hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, trisphenol,dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene,vinylnorbornaene, pinene, and limonene, but are not particularly limitedthereto. Herein, the resin of the present embodiment may be a bi orhigher (for example, bi to tetra) functional copolymer of the compoundrepresented by the formula (1) with the above-described phenols, may bea bi or higher (for example, bi to tetra) functional copolymer of thecompound represented by the formula (1) with the above-describedcopolymerizable monomer, or may be a ter or higher (for example, ter totetra) functional copolymer of the compound represented by the formula(1), the above-described phenols, and the above-describedcopolymerizable monomer.

Herein, the molecular weight of the resin of the present embodiment isnot particularly limited, and the weight average molecular weight (Mw)in terms of polystyrene is preferably 500 to 30000, and more preferably750 to 20000. In addition, the resin of the present embodimentpreferably has a dispersity (weight average molecular weight Mw/numberaverage molecular weight Mn) in a range from 1.2 to 7 from theviewpoints of improving a crosslinking efficiency and suppressing avolatile component during baking. Herein, the Mw and Mn can bedetermined by a method in Examples described later.

The compound represented by the formula (1) and/or the resin obtainedwith the compound as a monomer preferably have/has a high solubility inthe solvent from the viewpoint of making the application of a wetprocess easier. More specifically, when the solvent is1-methoxy-2-propanol (PGME) and/or propylene glycol monomethyl etheracetate (PGMEA), such a compound and/or resin preferably have/has asolubility of 10% by mass or more in the solvent. Herein, the solubilityin PGME and/or PGMEA is defined as “Mass of resin/(Mass of resin+Mass ofsolvent)×100 (% by mass)”. For example, in the case where 10 g of thecompound represented by the formula (1) and/or the resin obtained withthe compound as a monomer are/is evaluated to be dissolved in 90 g ofPGMEA, the solubility of the compound represented by the formula (1)and/or the resin obtained with the compound as a monomer in PGMEA is“10% by mass or more”, and in the case where the compound and/or theresin are/is evaluated not to be dissolved, the solubility is “less than10% by mass”

[Material for forming underlayer film for lithography]A material forforming an underlayer film for lithography of the present embodimentcontains at least one substance selected from the group consisting ofthe compound represented by the formula (1) of the present embodimentand the resin of the present embodiment. In the present embodiment, thecontent of the substance is preferably 1 to 100% by mass, morepreferably 10 to 100% by mass, further preferably 50 to 100% by mass,further preferably 100% by mass based on the total amount (100% by mass)of the material for forming an underlayer film for lithography, in termsof coatability and quality stability.

The material for forming an underlayer film for lithography of thepresent embodiment can be applied to a wet process, and is excellent inheat resistance and etching resistance. Furthermore, since the materialfor forming an underlayer film for lithography of the present embodimentis obtained by using the substance, the material can be used to form anunderlayer film whose degradation is suppressed at high-temperaturebaking and which is also excellent in etching resistance to oxygenplasma etching or the like. Furthermore, the material for forming anunderlayer film for lithography of the present embodiment is alsoexcellent in adhesiveness with a resist layer and therefore can providean excellent resist pattern. Herein, the material for forming anunderlayer film for lithography of the present embodiment may include aknown material for forming an underlayer film for lithography as long asthe effect of the present invention is not impaired.

[Composition for Forming Underlayer Film for Lithography]

A composition for forming an underlayer film for lithography of thepresent embodiment contains the material for forming an underlayer filmfor lithography, and a solvent.

[Solvent]

The solvent to be used in the present embodiment, which can beappropriately used, is a known one as long as such known one candissolve at least the compound represented by the above-describedformula (1) and/or the resin obtained with the compound as a monomer.

Specific examples of the solvent include ketone-based solvents such asacetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone;cellosolve-based solvents such as propylene glycol monomethyl ether andpropylene glycol monomethyl ether acetate; ester-based solvents such asethyl lactate, methyl acetate, ethyl acetate, butyl acetate, isoamylacetate, ethyl lactate, methyl methoxypropionate and methylhydroxyisobutyrate; alcohol-based solvents such as methanol, ethanol,isopropanol and 1-ethoxy-2-propanol; and aromatic hydrocarbons such astoluene, xylene and anisole, but are not particularly limited thereto.These organic solvents can be used singly or in combinations of two ormore thereof.

Among the solvents, preferable are cyclohexanone, propylene glycolmonomethyl ether, propylene glycol monomethyl ether acetate, ethyllactate, methyl hydroxyisobutyrate, and anisole, in terms of safety.

The content of the solvent is not particularly limited, but it ispreferably 100 to 10000 parts by mass, more preferably 200 to 5000 partsby mass, further preferably 200 to 1000 parts by mass based on 100 partsby mass of the material for forming an underlayer film in terms ofsolubility and film formation.

[Crosslinking Agent]

The composition for forming an underlayer film for lithography of thepresent embodiment may further contain, if necessary, a crosslinkingagent from the viewpoint of suppression of intermixing, and the like.Specific examples of the crosslinking agent usable in the presentembodiment include a melamine compound, a guanamine compound, aglycoluril compound, a urea compound, an epoxy compound, a thioepoxycompound, an isocyanate compound, an azide compound, and a compoundincluding a double bond such as an alkenyl ether group, these compoundsbeing substituted with at least one group selected from a methylolgroup, an alkoxymethyl group and an acyloxymethyl group, as asubstituent (crosslinkable group), but are not particularly limitedthereto. Herein, these crosslinking agents can be used singly or incombinations of two or more thereof. Such a crosslinking agent can alsobe used as an additive. Herein, the crosslinkable group may also beintroduced as a pendant group into a polymer side chain of the compoundrepresented by the formula (1) and/or the resin obtained with thecompound as a monomer. A compound including a hydroxy group can also beused as the crosslinking agent.

Specific examples of the melamine compound include hexamethylolmelamine,hexamethoxymethylmelamine, a compound in which 1 to 6 methylol groups inhexamethylolmelamine are methoxymethylated, or mixtures thereof, andhexamethoxyethylmelamine, hexaacyloxymethylmelamine, a compound in which1 to 6 methylol groups in hexamethylolmelamine are acyloxymethylated,and mixtures thereof. Specific examples of the epoxy compound includetris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether,trimethylolpropane triglycidyl ether, and triethylolethane triglycidylether.

Specific examples of the guanamine compound includetetramethylolguanamine, tetramethoxymethylguanamine, a compound in which1 to 4 methylol groups in tetramethylolguanamine are methoxymethylated,or mixtures thereof, and tetramethoxyethylguanamine,tetraacyloxyguanamine, a compound in which 1 to 4 methylol groups intetramethylolguanamine are acyloxymethylated, and mixtures thereof.Specific examples of the glycoluril compound includetetramethylolglycoluril, tetramethoxyglycoluril,tetramethoxymethylglycoluril, a compound in which 1 to 4 methylol groupsin tetramethylolglycoluril are methoxymethylated, and mixtures thereof,and a compound in which 1 to 4 methylol groups intetramethylolglycoluril are acyloxymethylated, and mixtures thereof.Specific examples of the urea compound include tetramethylolurea,tetramethoxymethylurea, a compound in which 1 to 4 methylol groups intetramethylolurea are methoxymethylated, and mixtures thereof, andtetramethoxyethylurea.

Specific examples of the compound including an alkenyl ether groupinclude ethylene glycol divinyl ether, triethylene glycol divinyl ether,1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether,tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether,trimethylolpropane trivinyl ether, hexanediol divinyl ether,1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether,pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitolpentavinyl ether, and trimethylolpropane trivinyl ether.

The content of the crosslinking agent in the material for forming anunderlayer film for lithography of the present embodiment is notparticularly limited, but it is preferably 5 to 50 parts by mass, morepreferably 10 to 40 parts by mass based on 100 parts by mass of thematerial for forming an underlayer film. The content is set within theabove preferable range to result in tendencies to suppress theoccurrence of the mixing phenomenon with the resist layer, and to resultin tendencies to enhance an antireflective effect and improve filmformability after crosslinking.

[Acid Generator]

The composition for forming an underlayer film for lithography of thepresent embodiment may further also contain, if necessary, an acidgenerator from the viewpoint of further promoting a crosslinkingreaction by heat. As the acid generator, one for generating an acid bypyrolysis and one for generating an acid by light irradiation are known,and any of them can be used.

The acid generator includes, for example:

1) an onium salt of the following general formula (P1a-1), (P1a-2),(P1a-3) and (P1b),2) a diazomethane derivative of the following general formula (P2),3) a glyoxime derivative of the following general formula (P3),4) a bissulfone derivative of the following general formula (P4),5) a sulfonic acid ester of an N-hydroxyimide compound of the followinggeneral formula (P5),6) a β-ketosulfonic acid derivative,7) a disulfone derivative,8) a nitrobenzylsulfonate derivative, and9) a sulfonic acid ester derivative, but is not particularly limitedthereto. Herein, these acid generators can be used alone, or two or morethereof can be used in combination.

In the formulae, each of R^(101a), R^(101b) and R^(101c) independentlyrepresents a straight, branched or cyclic alkyl group, alkenyl group,oxoalkyl group or oxoalkenyl group having 1 to 12 carbon atoms; an arylgroup having 6 to 20 carbon atoms; or an aralkyl group or aryloxoalkylgroup having 7 to 12 carbon atoms, and a part or all of hydrogen atomsof these groups may be substituted with an alkoxy group or the like. Inaddition, R^(101b) and R^(101c) may form a ring, and if forming a ring,each of R^(101b) and R^(101c) independently represents an alkylene grouphaving 1 to 6 carbon atoms. K⁻ represents a non-nucleophilic counterion. R^(101d), R^(101e), R^(101f) and R^(101g) are represented by eachindependently adding a hydrogen atom to R^(101a), R^(101b) and R^(101c).R^(101d) and R^(101e), and R^(101d), R^(101e) and R^(101f) may form aring, and if forming a ring, R^(101d) and R^(101e), and R^(101d),R^(101e) and R^(101f) represent an alkylene group having 3 to 10 carbonatoms, or a heteroaromatic ring having therein the nitrogen atom(s) inthe formula.

R^(101a), R^(101b), R^(101c), R^(101d), R^(101e), R^(101f) and R^(101g)described above may be the same or different from one another.Specifically, examples of the alkyl group include, but are not limitedto the following, a methyl group, an ethyl group, a propyl group, anisopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group,a pentyl group, a hexyl group, a heptyl group, an octyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, acyclopropylmethyl group, a 4-methyl cyclohexyl group, a cyclohexylmethylgroup, a norbornyl group, and an adamantyl group. Examples of thealkenyl group include, but are not limited to the following, a vinylgroup, an allyl group, a propenyl group, a butenyl group, a hexenylgroup, and a cyclohexenyl group. Examples of the oxoalkyl group caninclude, but are not limited to the following, a 2-oxocyclopentyl group,a 2-oxocyclohexyl group, a 2-oxopropyl group, a 2-cyclopentyl-2-oxoethylgroup, a 2-cyclohexyl-2-oxoethyl group, and a2-(4-methylcyclohexyl)-2-oxoethyl group. Examples of the oxoalkenylgroup include, but are not limited to the following, a2-oxo-4-cyclohexenyl group and a 2-oxo-4-propenyl group. Examples of thearyl group include, but are not limited to the following, a phenylgroup, a naphthyl group, alkoxyphenyl groups such as a p-methoxyphenylgroup, a m-methoxyphenyl group, an o-methoxyphenyl group, anethoxyphenyl group, a p-tert-butoxyphenyl group, and am-tert-butoxyphenyl group; alkylphenyl groups such as a 2-methylphenylgroup, a 3-methylphenyl group, a 4-methylphenyl group, an ethylphenylgroup, a 4-tert-butylphenyl group, a 4-butylphenyl group, and adimethylphenyl group; alkylnaphthyl groups such as a methylnaphthylgroup and an ethylnaphthyl group; alkoxynaphthyl groups such as amethoxynaphthyl group and an ethoxynaphthyl group; dialkylnaphthylgroups such as a dimethylnaphthyl group and a diethylnaphthyl group; anddialkoxynaphthyl groups such as a dimethoxynaphthyl group and adiethoxynaphthyl group. Examples of the aralkyl group include, but arenot limited to the following, a benzyl group, a phenylethyl group, and aphenethyl group. Examples of the aryloxoalkyl group include, but are notlimited to the following, 2-aryl-2-oxoethyl groups such as a2-phenyl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a2-(2-naphthyl)-2-oxoethyl group. Examples of the non-nucleophiliccounter ion, K⁻, include, but are not limited to the following, halideions such as a chloride ion and a bromide ion; fluoroalkyl sulfonatessuch as triflate, 1,1,1-trifluoroethane sulfonate, and nonafluorobutanesulfonate; aryl sulfonates such as tosylate, benzene sulfonate,4-fluorobenzene sulfonate, and 1,2,3,4,5-pentafluorobenzene sulfonate;and alkyl sulfonates such as mesylate and butane sulfonate.

In the case where R^(101d), R^(101e), R^(101f) and R^(101g) are each aheteroaromatic ring having the nitrogen atom(s) in the formula, examplesof the heteroaromatic ring include imidazole derivatives (for example,imidazole, 4-methylimidazole, and 4-methyl-2-phenylimidazole), pyrazolederivatives, furazan derivatives, pyrroline derivatives (for example,pyrroline and 2-methyl-1-pyrroline), pyrrolidine derivatives (forexample, pyrrolidine, N-methylpyrrolidine, pyrrolidinone, andN-methylpyrrolidone), imidazoline derivatives, imidazolidinederivatives, pyridine derivatives (for example, pyridine,methylpyridine, ethylpyridine, propylpyridine, butylpyridine,4-(1-butylpentyl)pyridine, dimethylpyridine, trimethylpyridine,triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridine,4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine,butoxypyridine, dimethoxypyridine, 1-methyl-2-pyridone,4-pyrrolidinopyridine, 1-methyl-4-phenylpyridine,2-(1-ethylpropyl)pyridine, aminopyridine, and dimethylaminopyridine),pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives,pyrazoline derivatives, pyrazolidine derivatives, piperidinederivatives, piperazine derivatives, morpholine derivatives, indolederivatives, isoindole derivatives, 1H-indazole derivatives, indolinederivatives, quinoline derivatives (for example, quinoline and3-quinolinecarbonitrile), isoquinoline derivatives, cinnolinederivatives, quinazoline derivatives, quinoxaline derivatives,phthalazine derivatives, purine derivatives, pteridin derivatives,carbazole derivatives, phenanthridine derivatives, acridine derivatives,phenazine derivatives, 1,10-phenanthroline derivatives, adeninederivatives, adenosine derivatives, guanine derivatives, guanosinederivatives, uracil derivative, and uridine derivatives.

The onium salts of the formula (P1a-1) and the formula (P1a-2) havefunctions as a photo acid generator and a thermal acid generator. Theonium salt of the formula (P1a-3) has a function as a thermal acidgenerator.

In the formula (P1b), each of R^(102a) and R^(102b) independentlyrepresents a straight, branched or cyclic alkyl group having 1 to 8carbon atoms. R¹⁰³ represents a straight, branched or cyclic alkylenegroup having 1 to 10 carbon atoms. Each of R^(104a) and R^(104b)independently represents a 2-oxoalkyl group having 3 to 7 carbon atoms.K⁻ represents a non-nucleophilic counter ion.

Specific examples of R^(102a) and R^(102b) include, but are not limitedto the following, a methyl group, an ethyl group, a propyl group, anisopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group,a pentyl group, a hexyl group, a heptyl group, an octyl group, acyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a4-methyl cyclohexyl group, and a cyclohexylmethyl group. Specificexamples of R¹⁰³ include, but are not limited to the following, amethylene group, an ethylene group, a propylene group, a butylene group,a pentylene group, a hexylene group, a heptylene group, an octylenegroup, a nonylene group, a 1,4-cyclohexylene group, a 1,2-cyclohexylenegroup, a 1,3-cyclopentylene group, a 1,4-cyclooctylene group, and a1,4-cyclohexanedimethylene group. Specific examples of R^(104a) andR^(104b) include, but are not limited to the following, a 2-oxopropylgroup, a 2-oxocyclopentyl group, a 2-oxocyclohexyl group, and a2-oxocycloheptyl group. K⁻ includes the same as those described in theformula (P1a-1), (P1a-2) and (P1a-3).

In formula (P2), each of R¹⁰⁵ and R¹⁰⁶ independently represents astraight, branched or cyclic alkyl group or halogenated alkyl grouphaving 1 to 12 carbon atoms, an aryl group or halogenated aryl grouphaving 6 to 20 carbon atoms, or an aralkyl group having 7 to 12 carbonatoms.

Examples of the alkyl group in each of R¹⁰⁵ and R¹⁰⁶ include, but arenot limited to the following, a methyl group, an ethyl group, a propylgroup, an isopropyl group, a n-butyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, a heptyl group, anoctyl group, an amyl group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a norbornyl group, and an adamantyl group. Examplesof the halogenated alkyl group include, but are not limited to thefollowing, a trifluoromethyl group, a 1,1,1-trifluoroethyl group, a1,1,1-trichloroethyl group, and a nonafluorobutyl group. Examples of thearyl group include, but are not limited to the following, alkoxyphenylgroups such as a phenyl group, a p-methoxyphenyl group, am-methoxyphenyl group, an o-methoxyphenyl group, an ethoxyphenyl group,a p-tert-butoxyphenyl group, and a m-tert-butoxyphenyl group; andalkylphenyl groups such as a 2-methylphenyl group, a 3-methylphenylgroup, a 4-methylphenyl group, an ethylphenyl group, a4-tert-butylphenyl group, a 4-butylphenyl group, and a dimethylphenylgroup. Examples of the halogenated aryl group include, but are notlimited to the following, a fluorophenyl group, a chlorophenyl group,and a 1,2,3,4,5-pentafluorophenyl group. Examples of the aralkyl groupinclude, but are not limited to the following, a benzyl group and aphenethyl group.

In the formula (P3), each of R¹⁰⁷, R¹⁰⁸ and R¹⁰⁹ independentlyrepresents a straight, branched or cyclic alkyl group or halogenatedalkyl group having 1 to 12 carbon atoms; an aryl group or halogenatedaryl group having 6 to 20 carbon atoms; or an aralkyl group having 7 to12 carbon atoms. R¹⁰⁸ and R¹⁰⁹ may be bonded with each other to form acyclic structure, and if forming a cyclic structure, each of R¹⁰⁸ andR¹⁰⁹ represents a straight or branched alkylene group having 1 to 6carbon atoms.

The alkyl group, halogenated alkyl group, aryl group, halogenated arylgroup, and aralkyl group in each of R¹⁰⁷, R¹⁰⁸ and R¹⁰⁹ include the sameas those described in R¹⁰⁵ and R¹⁰⁶. Herein, examples of the alkylenegroup in each of R¹⁰⁸ and R¹⁰⁹ include, but are not limited to thefollowing, a methylene group, an ethylene group, a propylene group, abutylene group, and a hexylene group.

In formula (P4), R^(101a) and R^(101b) are the same as R¹⁰⁷ in theformula (P3).

In the formula (P5), R¹¹⁰ represents an arylene group having 6 to 10carbon atoms, an alkylene group having 1 to 6 carbon atoms, or analkenylene group having 2 to 6 carbon atoms, and a part or all ofhydrogen atoms of these groups may be further substituted with astraight or branched alkyl group or alkoxy group having 1 to 4 carbonatoms, a nitro group, an acetyl group, or a phenyl group. R¹¹¹represents a straight, branched or substituted alkyl group, alkenylgroup or alkoxyalkyl group having 1 to 8 carbon atoms, a phenyl group,or a naphthyl group, and a part or all of hydrogen atoms of these groupsmay be further substituted with an alkyl group or alkoxy group having 1to 4 carbon atoms; a phenyl group that may be substituted with an alkylgroup or alkoxy group having 1 to 4 carbon atoms, a nitro group, or anacetyl group; a heteroaromatic group having 3 to 5 carbon atoms; or achlorine atom or a fluorine atom.

Herein, examples of the arylene group in R¹¹⁰ include, but are notlimited to the following, a 1,2-phenylene group and a 1,8-naphthylenegroup. Examples of the alkylene group include, but are not limited tothe following, a methylene group, an ethylene group, a trimethylenegroup, a tetramethylene group, a phenylethylene group, and anorbornane-2,3-diyl group. Examples of the alkenylene group include, butare not limited to the following, a 1,2-vinylene group, a1-phenyl-1,2-vinylene group, and a 5-norbornene-2,3-diyl group. Thealkyl group in R¹¹¹ includes the same as those in R^(101a) to R^(101c).Examples of the alkenyl group include, but are not limited to thefollowing, a vinyl group, a 1-propenyl group, an allyl group, a1-butenyl group, a 3-butenyl group, an isoprenyl group, a 1-pentenylgroup, a 3-pentenyl group, a 4-pentenyl group, a dimethylallyl group, a1-hexenyl group, a 3-hexenyl group, a 5-hexenyl group, a 1-heptenylgroup, a 3-heptenyl group, a 6-heptenyl group, and a 7-octenyl group.Examples of the alkoxyalkyl group include, but are not limited to thefollowing, a methoxymethyl group, an ethoxymethyl group, a propoxymethylgroup, a butoxymethyl group, a pentyloxymethyl group, a hexyloxymethylgroup, a heptyloxymethyl group, a methoxyethyl group, an ethoxyethylgroup, a propoxyethyl group, a butoxyethyl group, a pentyloxyethylgroup, a hexyloxyethyl group, a methoxypropyl group, an ethoxypropylgroup, a propoxypropyl group, a butoxypropyl group, a methoxybutylgroup, an ethoxybutyl group, a propoxybutyl group, a methoxypentylgroup, an ethoxypentyl group, a methoxyhexyl group, and a methoxyheptylgroup.

Herein, Examples of the alkyl group having 1 to 4 carbon atoms, whichmay be further substituted, include, but are not limited to thefollowing, a methyl group, an ethyl group, a propyl group, an isopropylgroup, a n-butyl group, a an isobutyl group, and a tert-butyl group.Examples of the alkoxy group having 1 to 4 carbon atoms include, but arenot limited to the following, a methoxy group, an ethoxy group, apropoxy group, an isopropoxy group, a n-butoxy group, an isobutoxygroup, and tert-butoxy group. Examples of the phenyl group that may besubstituted with an alkyl group or alkoxy group having 1 to 4 carbonatoms, a nitro group, or an acetyl group include, but are not limited tothe following, a phenyl group, a tolyl group, a p-tert-butoxyphenylgroup, a p-acetylphenyl group, and a p-nitrophenyl group. Examples ofthe heteroaromatic group having 3 to 5 carbon atoms include, but are notlimited to the following, a pyridyl group and a furyl group.

Specific examples of the acid generator include, but are not limited tothe following, onium salts such as tetramethylammoniumtrifluoromethanesulfonate, tetramethylammoniumnonafluorobutanesulfonate, triethylammonium nonafluorobutanesulfonate,pyridinium nonafluorobutanesulfonate, triethylammonium camphorsulfonate,pyridinium camphorsulfonate, tetra n-butylammoniumnonafluorobutanesulfonate, tetraphenylammoniumnonafluorobutanesulfonate, tetramethylammonium p-toluenesulfonate,diphenyliodonium trifluoromethanesulfonate,(p-tert-butoxyphenyl)phenyliodonium trifluoromethanesulfonate,diphenyliodonium p-toluenesulfonate, (p-tert-butoxyphenyl)phenyliodoniump-toluenesulfonate, triphenylsulfonium trifluoromethanesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium trifluoromethanesulfonate,bis(p-tert-butoxyphenyl)phenylsulfonium trifluoromethanesulfonate,tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate,triphenylsulfonium p-toluenesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,bis(p-tert-butoxyphenyl)phenylsulfonium p-toluenesulfonate,tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfoniumbutanesulfonate, trimethylsulfonium trifluoromethanesulfonate,trimethylsulfonium p-toluenesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium p-toluenesulfonate,dimethylphenylsulfonium trifluoromethanesulfonate,dimethylphenylsulfonium p-toluenesulfonate, dicyclohexylphenylsulfoniumtrifluoromethanesulfonate, dicyclohexylphenylsulfoniump-toluenesulfonate, trinaphthylsulfonium trifluoromethanesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,(2-norbornyl)methyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,ethylene bis[methyl(2-oxocyclopentyl)sulfoniumtrifluoromethanesulfonate], and1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate; diazomethanederivatives such as bis(benzenesulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane, bis(xylenesulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,bis(cyclopentylsulfonyl)diazomethane, bis(n-butylsulfonyl)diazomethane,bis(isobutylsulfonyl)diazomethane, bis(sec-butylsulfonyl)diazomethane,bis(n-propylsulfonyl)diazomethane, bis(isopropylsulfonyl)diazomethane,bis(tert-butylsulfonyl)diazomethane, bis(n-amylsulfonyl)diazomethane,bis(isoamylsulfonyl)diazomethane, bis(sec-amylsulfonyl)diazomethane,bis(tert-amylsulfonyl)diazomethane,1-cyclohexylsulfonyl-1-(tert-butylsulfonyl)diazomethane,1-cyclohexylsulfonyl-1-(tert-amylsulfonyl)diazomethane, and1-tert-amylsulfonyl-1-(tert-butylsulfonyl)diazomethane; glyoximederivatives such as bis-(p-toluenesulfonyl)-α-dimethylglyoxime,bis-(p-toluesulfonyl)-α-diphenylglyoxime,bis-(p-toluenesulfonyl)-α-dicyclohexylglyoxime,bis-(p-toluenesulfonyl)-2,3-pentanedioneglyoxime,bis-(p-toluenesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,bis-(n-butanesulfonyl)-α-dimethylglyoxime,bis-(n-butanesulfonyl)-α-diphenylglyoxime,bis-(n-butanesulfonyl)-α-dicyclohexylglyoxime,bis-(n-butanesulfonyl)-2,3-pentanedioneglyoxime,bis-(n-butanesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,bis-(methanesulfonyl)-α-dimethylglyoxime,bis-(trifluoromethanesulfonyl)-α-dimethylglyoxime,bis-(1,1,1-trifluoroethanesulfonyl)-α-dimethylglyoxime,bis-(tert-butanesulfonyl)-α-dimethylglyoxime,bis-(perfluorooctanesulfonyl)-α-dimethylglyoxime,bis-(cyclohexanesulfonyl)-α-dimethylglyoxime,bis-(benzenesulfonyl)-α-dimethylglyoxime,bis-(p-fluorobenzenesulfonyl)-α-dimethylglyoxime,bis-(p-tert-butylbenzenesulfonyl)-α-dimethylglyoxime,bis-(xylenesulfonyl)-α-dimethylglyoxime, andbis-(camphorsulfonyl)-α-dimethylglyoxime; bissulfone derivatives, suchas bisnaphthylsulfonylmethane, bistrifluoromethylsulfonylmethane,bismethylsulfonylmethane, bisethylsulfonylmethane,bispropylsulfonylmethane, bisisopropylsulfonylmethane,bis-p-toluenesulfonylmethane, and bisbenzenesulfonylmethane;β-ketosulfone derivatives such as2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane and2-isopropylcarbonyl-2-(p-toluenesulfonyl)propane; disulfone derivativessuch as a diphenyldisulfone derivative and a dicyclohexyldisulfonederivative, nitrobenzylsulfonate derivatives such as 2,6-dinitrobenzylp-toluenesulfonate and 2,4-dinitrobenzyl p-toluenesulfonate; sulfonicacid ester derivatives such as 1,2,3-tris(methanesulfonyloxy)benzene,1,2,3-tris(trifluoromethanesulfonyloxy)benzene, and1,2,3-tris(p-toluenesulfonyloxy)benzene; and sulfonic acid esterderivatives of a N-hydroxyimide compound, such as N-hydroxysuccinimidemethanesulfonic acid ester, N-hydroxysuccinimidetrifluoromethanesulfonic acid ester, N-hydroxysuccinimide ethanesulfonicacid ester, N-hydroxysuccinimide 1-propanesulfonic acid ester,N-hydroxysuccinimide 2-propanesulfonic acid ester, N-hydroxysuccinimide1-pentanesulfonic acid ester, N-hydroxysuccinimide 1-octanesulfonic acidester, N-hydroxysuccinimide p-toluenesulfonic acid ester,N-hydroxysuccinimide p-methoxybenzenesulfonic acid ester,N-hydroxysuccinimide 2-chloroethanesulfonic acid ester,N-hydroxysuccinimide benzenesulfonic acid ester,N-hydroxysuccinimide-2,4,6-trimethylbenzenesulfonic acid ester,N-hydroxysuccinimide 1-naphthalenesulfonic acid ester,N-hydroxysuccinimide 2-naphthalenesulfonic acid ester,N-hydroxy-2-phenylsuccinimide methanesulfonic acid ester,N-hydroxymaleimide methanesulfonic acid ester, N-hydroxymaleimideethanesulfonic acid ester, N-hydroxy-2-phenylmaleimide methanesulfonicacid ester, N-hydroxyglutarimide methanesulfonic acid ester,N-hydroxyglutarimide benzenesulfonic acid ester, N-hydroxyphthalimidemethanesulfonic acid ester, N-hydroxyphthalimide benzenesulfonic acidester, N-hydroxyphthalimide trifluoromethanesulfonic acid ester,N-hydroxyphthalimide p-toluenesulfonic acid ester,N-hydroxynaphthalimide methanesulfonic acid ester,N-hydroxynaphthalimide benzenesulfonic acid ester,N-hydroxy-5-norbornene-2,3-dicarboxyimide methanesulfonic acid ester,N-hydroxy-5-norbornene-2,3-dicarboxyimide trifluoromethanesulfonic acidester, and N-hydroxy-5-norbornene-2,3-dicarboxyimide p-toluenesulfonicacid ester.

Among those described above, onium salts such as triphenylsulfoniumtrifluoromethanesulfonate, (p-tert-butoxyphenyl)diphenylsulfoniumtrifluoromethanesulfonate, tris(p-tert-butoxyphenyl)sulfoniumtrifluoromethanesulfonate, triphenylsulfonium p-toluenesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,trinaphthylsulfonium trifluoromethanesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,(2-norbornyl)methyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,and 1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate;diazomethane derivatives such as bis(benzenesulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane,bis(n-butylsulfonyl)diazomethane, bis(isobutylsulfonyl)diazomethane,bis(sec-butylsulfonyl)diazomethane, bis(n-propylsulfonyl)diazomethane,bis(isopropylsulfonyl)diazomethane, andbis(tert-butylsulfonyl)diazomethane; glyoxime derivatives such asbis-(p-toluenesulfonyl)-α-dimethylglyoxime andbis-(n-butanesulfonyl)-α-dimethylglyoxime, bissulfone derivatives suchas bisnaphthylsulfonylmethane; and sulfonic acid ester derivatives of anN-hydroxyimide compound, such as N-hydroxysuccinimide methanesulfonicacid ester, N-hydroxysuccinimide trifluoromethanesulfonic acid ester,N-hydroxysuccinimide 1-propanesulfonic acid ester, N-hydroxysuccinimide2-propanesulfonic acid ester, N-hydroxysuccinimide 1-pentanesulfonicacid ester, N-hydroxysuccinimide p-toluenesulfonic acid ester,N-hydroxynaphthalimide methanesulfonic acid ester, andN-hydroxynaphthalimide benzenesulfonic acid ester, and the like arepreferably used.

In the material for forming an underlayer film for lithography accordingto the present embodiment, the content of the acid generator is notparticularly limited, but the content is preferably 0.1 to 50 parts bymass and more preferably 0.5 to 40 parts by mass based on 100 parts bymass of the material for forming an underlayer film. The content is setwithin the above range to result in a tendency to increase the acidgeneration amount to promote a crosslinking reaction, and also to resultin a tendency to suppress the occurrence of the mixing phenomenon with aresist layer.

[Basic Compound]

The composition for forming an underlayer film for lithography of thepresent embodiment may further contain a basic compound from theviewpoint of improving preservation stability.

The basic compound serves as a quencher to an acid for suppressing atrace amount of the acid generated from the acid generator frompromoting a crosslinking reaction. Examples of such a basic compoundinclude primary, secondary, and tertiary aliphatic amines, mixed amines,aromatic amines, heterocyclic amines, a nitrogen-containing compoundhaving a carboxy group, a nitrogen-containing compound having a sulfonylgroup, a nitrogen-containing compound having a hydroxyl group, anitrogen-containing compound having a hydroxyphenyl group, an alcoholicnitrogen-containing compound, an amide derivative, and an imidederivative, but are not particularly limited thereto.

Specific examples of the primary aliphatic amines include, but are notlimited to the following, ammonia, methylamine, ethylamine,n-propylamine, isopropylamine, n-butylamine, isobutylamine,sec-butylamine, tert-butylamine, pentylamine, tert-amylamine,cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine,nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine,ethylenediamine, and tetraethylenepentamine. Specific examples of thesecondary aliphatic amines include, but are not limited to thefollowing, dimethylamine, diethylamine, di-n-propylamine,diisopropylamine, di-n-butylamine, diisobutylamine, di-sec-butylamine,dipentylamine, dicyclopentylamine, dihexylamine, dicyclohexylamine,diheptylamine, dioctylamine, dinonylamine, didecylamine, didodecylamine,dicetylamine, N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine,and N,N-dimethyltetraethylenepentamine. Specific examples of thetertiary aliphatic amines include, but are not limited to the following,trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine,tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tripentylamine,tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, tridodecylamine,tricetylamine, N,N,N′,N′-tetramethylmethylenediamine,N,N,N′,N′-tetramethylethylenediamine, andN,N,N′,N′-tetramethyltetraethylenepentamine.

Specific examples of the mixed amines include, but are not limited tothe following, dimethylethylamine, methylethylpropylamine, benzylamine,phenethylamine, and benzyldimethylamine. Specific examples of thearomatic amines and heterocyclic amines include, but are not limited tothe following, aniline derivatives (for example, aniline,N-methylaniline, N-ethylaniline, N-propylaniline, N,N-dimethylaniline,2-methylaniline, 3-methylaniline, 4-methylaniline, ethylaniline,propylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline,4-nitroaniline, 2,4-dinitroaniline, 2,6-dinitroaniline,3,5-dinitroaniline, and N,N-dimethyltoluidine), diphenyl(p-tolyl)amine,methyldiphenylamine, triphenylamine, phenylenediamine, naphthylamine,diaminonaphthalene, pyrrole derivatives (for example, pyrrole,2H-pyrrole, 1-methylpyrrole, 2,4-dimethylpyrrole, 2,5-dimethylpyrrole,and N-methylpyrrole), oxazole derivatives (for example, oxazole andisoxazole), thiazole derivatives (for example, thiazole andisothiazole), imidazole derivatives (for example, imidazole,4-methylimidazole, and 4-methyl-2-phenylimidazole), pyrazolederivatives, furazan derivatives, pyrroline derivatives (for example,pyrroline and 2-methyl-1-pyrroline), pyrrolidine derivatives (forexample, pyrrolidine, N-methylpyrrolidine, pyrrolidinone, andN-methylpyrrolidone), imidazoline derivatives, imidazolidinederivatives, pyridine derivatives (for example, pyridine,methylpyridine, ethylpyridine, propylpyridine, butylpyridine,4-(1-butylpentyl)pyridine, dimethylpyridine, trimethylpyridine,triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridine,4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine,butoxypyridine, dimethoxypyridine, 1-methyl-2-pyridone,4-pyrrolidinopyridine, 1-methyl-4-phenylpyridine,2-(1-ethylpropyl)pyridine, aminopyridine, and dimethylaminopyridine),pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives,pyrazoline derivatives, pyrazolidine derivatives, piperidinederivatives, piperazine derivatives, morpholine derivatives, indolederivatives, isoindole derivatives, 1H-indazole derivatives, indolinederivatives, quinoline derivatives (for example, quinoline,3-quinolinecarbonitrile), isoquinoline derivatives, cinnolinederivatives, quinazoline derivatives, quinoxaline derivatives,phthalazine derivatives, purine derivatives, pteridin derivatives,carbazole derivatives, phenanthridine derivatives, acridine derivatives,phenazine derivatives, 1,10-phenanthroline derivatives, adeninederivatives, adenosine derivatives, guanine derivatives, guanosinederivatives, uracil derivatives, and uridine derivatives.

Furthermore, specific examples of the nitrogen-containing compoundhaving a carboxy group include, but are not limited to the following,aminobenzoic acid, indolecarboxylic acid, and amino acid derivatives(for example, nicotinic acid, alanine, arginine, aspartic acid, glutamicacid, glycine, histidine, isoleucine, glycylleucine, leucine,methionine, phenylalanine, threonine, lysine,3-aminopyrazine-2-carboxylic acid, and methoxyalanine). Specificexamples of the nitrogen-containing compound having a sulfonyl groupinclude, but are not limited to the following, 3-pyridinesulfonic acidand pyridinium p-toluenesulfonate. Specific examples of thenitrogen-containing compound having a hydroxyl group, thenitrogen-containing compound having a hydroxyphenyl group, and thealcoholic nitrogen-containing compound include, but are not limited tothe following, 2-hydroxypyridine, aminocresol, 2,4-quinolinediol,3-indolemethanol hydrate, monoethanolamine, diethanolamine,triethanolamine, N-ethyldiethanolamine, N,N-diethylethanolamine,triisopropanolamine, 2,2′-iminodiethanol, 2-aminoethanol,3-amino-1-propanol, 4-amino-1-butanol, 4-(2-hydroxyethyl)morpholine,2-(2-hydroxyethyl)pyridine, 1-(2-hydroxyethyl)piperazine,1-[2-(2-hydroxyethoxy)ethyl]piperazine, piperidine ethanol,1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)-2-pyrrolidone,3-piperidino-1,2-propanediol, 3-pyrrolidino-1,2-propanediol,8-hydroxyjulolidine, 3-quinuclidinol, 3-tropanol, 1-methyl-2-pyrrolidineethanol, 1-aziridine ethanol, N-(2-hydroxyethyl)phthalimide, andN-(2-hydroxyethyl)isonicotinamide. Specific examples of the amidederivative include, but are not limited to the following, formamide,N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide,N,N-dimethylacetamide, propionamide, and benzamide. Specific examples ofthe imide derivative include, but are not limited to the following,phthalimide, succinimide, and maleimide.

In the composition for forming an underlayer film for lithographyaccording to the present embodiment, the content of the basic compoundis not particularly limited, but the content is preferably 0.001 to 2parts by mass and more preferably 0.01 to 1 part by mass based on 100parts by mass of the material for forming an underlayer film. Thecontent is set within the above preferable range to result in a tendencyto improve preservation stability without excessively interrupting acrosslinking reaction.

[Other Additives]

In addition, the composition for forming an underlayer film forlithography of the present embodiment may further contain other resinsand/or compounds for the purposes of imparting heat curability andcontrolling absorbance. Examples of such other resins and/or compoundsinclude naphthol resins, xylene resins naphthol-modified resins,phenol-modified resins of naphthalene resins, polyhydroxystyrene,dicyclopentadiene resins, (meth)acrylate, dimethacrylate,trimethacrylate, tetramethacrylate, resins having a naphthalene ringsuch as vinylnaphthalene and polyacenaphthylene, resins having abiphenyl ring such as phenanthrenequinone and fluorene, resins having aheterocyclic ring having a hetero atom such as thiophene and indene, andresins not containing an aromatic ring; rosin-based resins, and resinsor compounds including an alicyclic structure, such as cyclodextrin,adamantane(poly)ol, tricyclodecane(poly)ol and derivatives thereof, butare not particularly limited thereto. Furthermore, the material forforming an underlayer film for lithography of the present embodiment canalso contain a known additive. Examples of the known additive includes,but not limited to the following, an ultraviolet absorber, a surfactant,a colorant and a non-ionic surfactant.

[Underlayer Film for Lithography and Forming Method of Multilayer ResistPattern]

An underlayer film for lithography of the present embodiment is formedfrom the composition for forming an underlayer film for lithography ofthe present embodiment.

In addition, a resist pattern forming method of the present embodimentincludes step (A-1) of forming an underlayer film on a substrate byusing the composition for forming an underlayer film for lithography ofthe present embodiment, step (A-2) of forming at least one photoresistlayer on the underlayer film, and step (A-3) of irradiating apredetermined region of the photoresist layer with radiation, anddeveloping it.

Furthermore, a circuit pattern forming method of the present embodimentincludes step (B-1) of forming an underlayer film on a substrate byusing the composition for forming an underlayer film for lithography ofthe present embodiment, step (B-2) of forming an intermediate layer filmon the underlayer film by using a silicon atom-containing resistintermediate layer film material, step (B-3) of forming at least onephotoresist layer on the intermediate layer film, step (B-4) ofirradiating a predetermined region of the photoresist layer withradiation, and developing it to form a resist pattern, step (B-5) ofetching the intermediate layer film with the resist pattern as a mask,to form an intermediate layer film pattern, step (B-6) of etching theunderlayer film with the intermediate layer film pattern as an etchingmask, to form an underlayer film pattern, and step (B-7) of etching thesubstrate with the underlayer film pattern as an etching mask, to form apattern on the substrate.

The underlayer film for lithography of the present embodiment is notparticularly limited in terms of the forming method thereof as long asit is formed from the composition for forming an underlayer film forlithography of the present embodiment, and a known method can beapplied. For example, the underlayer film can be formed by applying thecomposition for forming an underlayer film for lithography of thepresent embodiment on the substrate by a known coating method orprinting method such as spin coating or screen printing, and removing anorganic solvent by volatilization or the like.

The underlayer film is preferably baked upon forming in order tosuppress the occurrence of the mixing phenomenon with an upperlayerresist and also promote a crosslinking reaction. In this case, thebaking temperature is not particularly limited, but it is preferablywithin the range of 80 to 450° C., and more preferably 200 to 400° C. Inaddition, the baking time is not also particularly limited, but ispreferably within the range of 10 to 300 seconds. Herein, the thicknessof the underlayer film can be appropriately selected depending on therequired properties, and is not particularly limited, but the thicknessis usually preferably about 30 to 20000 nm and more preferably 50 to15000 nm.

After the underlayer film is prepared, in the case of a two-layerprocess, a silicon-containing resist layer or a usual single-layerresist including a hydrocarbon is preferably prepared on the underlayerfilm, and in the case of a three-layer process, a silicon-containingintermediate layer is preferably prepared on the underlayer film, and asingle-layer resist layer not containing silicon is preferably preparedon the silicon-containing intermediate layer. In these cases, aphotoresist material for forming the resist layer, which can be used, isa known one.

After the underlayer film is prepared on the substrate, in the case of atwo-layer process, a silicon-containing resist layer or a usualsingle-layer resist including a hydrocarbon can be prepared on theunderlayer film. In the case of a three-layer process, asilicon-containing intermediate layer can be prepared on the underlayerfilm, and a single-layer resist layer not containing silicon can beprepared on the silicon-containing intermediate layer. In these cases, aphotoresist material for forming the resist layer, which can be used, isappropriately selected from known ones, and is not particularly limited.

As the silicon-containing resist material for a two-layer process, apositive-type photoresist material is preferably used, which contains asilicon atom-containing polymer such as a polysilsesquioxane derivativeor a vinylsilane derivative used as a base polymer in the viewpoint ofoxygen gas-etching resistance, and an organic solvent, an acid generatorand if necessary a basic compound. Herein, as the siliconatom-containing polymer, a known polymer used in such a resist materialcan be used.

As the silicon-containing intermediate layer for a three-layer process,a polysilsesquioxane-based intermediate layer is preferably used. Theintermediate layer is allowed to have an effect as an antireflectivefilm, and thus tends to make it possible to effectively suppressreflection. For example, if a material including many aromatic groupsand having a high substrate-etching resistance is used for theunderlayer film in a 193 nm exposure process, a k-value tends to beincreased to increase substrate reflection, but the reflection can besuppressed by the intermediate layer to thereby make the substratereflection 0.5% or less. For the intermediate layer having such anantireflection effect, but not limited to the following,polysilsesquioxane into which a phenyl group or a light-absorbing grouphaving a silicon-silicon bond for 193 nm exposure is introduced andwhich is to be crosslinked with an acid or heat is preferably used.

An intermediate layer formed by the Chemical Vapour Deposition (CVD)method can also be used. As the intermediate layer having a high effectas an antireflective film, prepared by the CVD method, but not limitedto the following, for example, a SiON film is known. In general, theintermediate layer is formed by a wet process such as a spin coatingmethod or screen printing rather than the CVD method in terms ofsimplicity and cost effectiveness. Herein, the upperlayer resist in athree-layer process may be of positive-type or negative-type, and thesame one as a commonly used single-layer resist can be used therefor.

Furthermore, the underlayer film of the present embodiment can also beused as a usual antireflective film for use in a single-layer resist ora usual underlying material for suppressing pattern collapse. Theunderlayer film of the present embodiment can also be expected to serveas a hard mask for underlying processing because of being excellent inetching resistance for underlying processing.

In the case where a resist layer is formed by the photoresist material,a wet process such as a spin coating method or screen printing ispreferably used as in the case of forming the underlayer film. Theresist material is coated by a spin coating method or the like and thenusually pre-baked, and such pre-baking is preferably performed in therange of 80 to 180° C. for 10 to 300 seconds. Thereafter, in accordancewith an ordinary method, the resultant can be subjected to exposure,post-exposure bake (PEB), and development to obtain a resist pattern.Herein, the thickness of the resist film is not particularly limited,but generally, it is preferably 30 to 500 nm and more preferably 50 to400 nm.

Light for use in exposure may be appropriately selected depending on thephotoresist material to be used. Examples of the light for use inexposure can include high energy radiation having a wavelength of 300 nmor less, specifically, excimer lasers of 248 nm, 193 nm, and 157 nm, asoft X-ray of 3 to 20 nm, electron beam, and an X-ray.

The resist pattern formed by the above method is a pattern whosecollapse is suppressed by the underlayer film of the present embodiment.Therefore, the underlayer film of the present embodiment can be used tothereby obtain a finer pattern, and an exposure amount necessary forobtaining such a resist pattern can be reduced.

Then, the obtained resist pattern is used as a mask to perform etching.As the etching of the underlayer film in a two-layer process, gasetching is preferably used. As the gas etching, etching using oxygen gasis suitable. In addition to oxygen gas, an inert gas such as He and Ar,and CO, CO₂, NH₃, SO₂, N₂, NO₂, and H₂ gases can also be added. The gasetching can also be performed not using oxygen gas but using only CO,CO₂, NH₃, N₂, NO₂, and H₂ gases. In particular, the latter gases arepreferably used for protecting a side wall for preventing a pattern sidewall from being undercut.

On the other hand, also in the etching of the intermediate layer in athree-layer process, gas etching is preferably used. As the gas etching,the same one as the one described in a two-layer process can be applied.In particular, the intermediate layer is preferably processed in athree-layer process using a fluorocarbon gas with the resist pattern asa mask. Thereafter, as described above, the intermediate layer patternis used as a mask to perform, for example, oxygen gas etching, therebyprocessing the underlayer film.

Herein, in the case where an inorganic hard mask intermediate layer filmis formed as the intermediate layer, a silicon oxide film, a siliconnitride film, and a silicon oxynitride film (SiON film) are formed bythe CVD method, the ALD method, and the like. The nitride film formingmethod that can be used is, but not limited to the following, any methoddescribed in, for example, Japanese Patent Laid-Open No. 2002-334869(Patent Literature 6) and WO2004/066377 (Patent Literature 7). While thephotoresist film can be directly formed on such an intermediate layerfilm, an organic antireflective film (BARC) may also be formed on theintermediate layer film by spin coating, and the photoresist film mayalso be formed thereon.

As the intermediate layer, a polysilsesquioxane-based intermediate layeris also preferably used. The resist intermediate layer film is allowedto have an effect as an antireflective film, and thus tends to make itpossible to effectively suppress reflection. A specific material for thepolysilsesquioxane-based intermediate layer that can be used is, but notlimited to the following, any material described in, for example,Japanese Patent Laid-Open No. 2007-226170 (Patent Literature 8) andJapanese Patent Laid-Open No. 2007-226204 (Patent Literature 9).

The next etching of the substrate can also be performed by an ordinarymethod, and, for example, when the substrate is made of SiO₂ or SiN,etching with mainly a fluorocarbon gas can be performed, and when thesubstrate is made of p-Si, Al, or W, etching mainly using achlorine-based gas or bromine-based gas can be performed. In the casewhere the substrate is processed by the etching with a fluorocarbon gas,the silicon-containing resist in a two-layer resist process and thesilicon-containing intermediate layer in a three-layer process arepeeled off at the same time as the processing of the substrate. On theother hand, in the case where the substrate is processed by the etchingwith a chlorine-based gas or bromine-based gas, the silicon-containingresist layer or the silicon-containing intermediate layer is peeled offseparately, and is generally peeled off by dry etching with afluorocarbon gas after the substrate is processed.

The underlayer film of the present embodiment is characterized by beingexcellent in etching resistance of such a substrate. The substrate thatcan be used is appropriately selected from known ones, and is notparticularly limited, but examples thereof include Si, a-Si, p-Si, SiO₂,SiN, SiON, W, TiN, and Al substrates. In addition, the substrate mayalso be a laminate having a processed film (processed substrate) on abase material (support). Examples of such a processed film includevarious Low-k films made of Si, SiO₂, SiON, SiN, p-Si, a-Si, W, W—Si,Al, Cu, and Al—Si, and stopper films thereof, and a material differentfrom the base material (support) is preferably used therefor. Herein,the thickness of the substrate to be processed or the processed film isnot particularly limited, but it is preferably about 50 to 10000 nm,more preferably 75 to 5000 nm.

[Purification Method of Compound or Resin]

A purification method of the compound or the resin of the presentembodiment includes a step of bringing a solution including the compoundrepresented by the formula (1) or the resin with the compound as amonomer and an organic solvent optionally immiscible with water intocontact with an acidic aqueous solution, to thereby extract the compoundor the resin. The step can allow the compound or the resin to bepurified by transferring a metal content included in the solution (A)including the compound or the resin and the organic solvent to anaqueous phase, and then separating an organic phase and the aqueousphase. The purification method of the present embodiment can allow thecontents of various metals in the compound represented by the formula(1) or the resin with the compound as a monomer to be remarkablyreduced.

The organic solvent optionally immiscible with water, to be used in thepresent embodiment, is not particularly limited, but it is preferably anorganic solvent that can be safely applied to a semiconductormanufacturing process. The amount of the organic solvent to be used ispreferably about 1 to 100 times the amount of the compound representedby the formula (1) or the resin obtained with the compound as a monomer,to be used.

Specific examples of the solvent to be used include, but are notparticularly limited, ethers such as diethyl ether and diisopropylether, esters such as ethyl acetate, n-butyl acetate and isoamylacetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone,ethyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-heptanone and2-pentanone, glycol ether acetates such as ethylene glycol monoethylether acetate, ethylene glycol monobutyl ether acetate, propylene glycolmonomethyl ether acetate (PGMEA) and propylene glycol monoethyl etheracetate, aliphatic hydrocarbons such as n-hexane and n-heptane, aromatichydrocarbons such as toluene and xylene, and halogenated hydrocarbonssuch as methylene chloride and chloroform. Among them, toluene,2-heptanone, cyclohexanone, cyclopentanone, methyl isobutyl ketone,propylene glycol monomethyl ether acetate, and ethyl acetate arepreferable, and cyclohexanone and propylene glycol monomethyl etheracetate are more preferable. These solvents can be used singly or as amixture of two or more thereof.

The acidic aqueous solution to be used in the present embodiment isappropriately selected from aqueous solutions in which an organic orinorganic compound commonly known is dissolved in water. Examplesinclude an aqueous solution in which a mineral acid such as hydrochloricacid, sulfuric acid, nitric acid or phosphoric acid is dissolved inwater, or an aqueous solution in which an organic acid such as aceticacid, propionic acid, oxalic acid, malonic acid, succinic acid, fumaricacid, maleic acid, tartaric acid, citric acid, methanesulfonic acid,phenolsulfonic acid, p-toluenesulfonic acid or trifluoroacetic acid isdissolved in water. These acidic aqueous solutions can be used singly orin combinations of two or more thereof. Among these acidic aqueoussolutions, an aqueous solution of at least one mineral acid selectedfrom the group consisting of hydrochloric acid, sulfuric acid, nitricacid and phosphoric acid, or an aqueous solution of at least one organicacid selected from the group consisting of acetic acid, propionic acid,oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid,tartaric acid, citric acid, methanesulfonic acid, phenolsulfonic acid,p-toluenesulfonic acid and trifluoroacetic acid is preferable, anaqueous solution of sulfuric acid, nitric acid, and a carboxylic acidsuch as acetic acid, oxalic acid, tartaric acid or citric acid is morepreferable, an aqueous solution of sulfuric acid, oxalic acid, tartaricacid or citric acid is further preferable, and an aqueous solution ofoxalic acid is further preferable. It is considered that a polyvalentcarboxylic acid such as oxalic acid, tartaric acid and citric acid iscoordinated with a metal ion to exert a chelating effect and thereforecan allow a metal to be more effectively removed. In addition, the waterto be here used is preferably water having a low metal content accordingto the purpose of the present invention, such as ion-exchange water.

The pH of the acidic aqueous solution to be used in the presentembodiment is not particularly limited, but a too high acidity of theaqueous solution is not preferable because of having an adverse effecton the compound represented by the formula (1) or the resin with thecompound as a monomer, in some cases. The pH preferably ranges fromabout 0 to 5, more preferably about 0 to 3.

The amount of the acidic aqueous solution to be used in the presentembodiment is not particularly limited, but, when the amount is 10% bymass or more, there tends to eliminate the need for an increase in thenumber of extractions for metal removal, and when the amount is 200% bymass or less, there tends to not excessively increase the total amountof the liquid, hardly causing an operational problem. The amount of theaqueous solution to be used is preferably 10 to 200% by mass, morepreferably 20 to 100% by mass based on the total amount (100% by mass)of the solution of the compound represented by the formula (1) or theresin with the compound as a monomer, dissolved in the organic solvent.

In the present embodiment, the acidic aqueous solution is brought intocontact with the solution (A) including the compound represented by theformula (1) or the resin obtained with the compound as a monomer and theorganic solvent optionally immiscible with water, to thereby extract themetal content.

The temperature in performing of the extraction treatment is preferablyin the range from 20 to 90° C., more preferably 30 to 80° C. Theextraction operation is performed by, for example, well mixing withstirring or the like and thereafter standing. Thus, the metal contentincluded in the solution including the compound represented by theformula (1) or the resin obtained with the compound as a monomer and theorganic solvent is transferred to the aqueous phase. In addition, theoperation can allow the acidity of the solution to be reduced,suppressing the change of properties of the compound represented by theformula (1) or the resin obtained with the compound as a monomer.

The resulting mixture is separated to the solution phase including thecompound represented by the formula (1) or the resin obtained with thecompound as a monomer and the organic solvent, and the aqueous phase,and therefore the solution including the compound represented by theformula (1) or the resin obtained with the compound as a monomer and theorganic solvent is recovered by decantation or the like. The standingtime is not particularly limited, but a too short standing time is notpreferable because separation to the solution phase including theorganic solvent, and the aqueous phase is deteriorated. The standingtime is preferably 1 minute or more, more preferably 10 minutes or more,further preferably 30 minutes or more. In addition, the extractiontreatment may be performed only once, but is also effectively performedwith operations such as mixing, standing and separation being repeatedlyperformed multiple times.

The purification method of the present embodiment preferably furtherincludes a step of, after the extraction step, subjecting the solution(A) including the compound represented by the formula (1) or the resinwith the compound as a monomer, extracted and recovered from the acidicaqueous solution, and the organic solvent, to an extraction with water,to extract the compound or the resin. The extraction operation isperformed by well mixing with stirring or the like and thereafterstanding. The resulting solution is separated to the solution phaseincluding the compound represented by the formula (1) or the resin withthe compound as a monomer and the organic solvent, and the aqueousphase, and therefore the solution phase including the compoundrepresented by the formula (1) or the resin with the compound as amonomer and the organic solvent is recovered by decantation or the like.In addition, the water to be here used is preferably water having a lowmetal content according to the purpose of the present invention, such asion-exchange water. The extraction treatment may be performed only once,but is also effectively performed with operations such as mixing,standing and separation being repeatedly performed multiple times. Inaddition, conditions in the extraction treatment, such as the ratio ofboth to be used, the temperature and the time, are not particularlylimited, but may be the same as in the case of the contact treatmentwith the acidic aqueous solution above.

The water content incorporated in the solution including the compoundrepresented by the formula (1) or the resin obtained with the compoundas a monomer and the organic solvent, thus obtained, can be easilyremoved by performing an operation such as distillation under reducedpressure. In addition, an organic solvent can be if necessary added toadjust the concentration of the compound represented by the formula (1)or the resin obtained with the compound as a monomer to anyconcentration.

The method of obtaining only the compound represented by the formula (1)or the resin with the compound as a monomer from the resulting solutionincluding the compound represented by the formula (1) or the resin withthe compound as a monomer and the organic solvent can be performed by aknown method such as removal under reduced pressure, separation byreprecipitation and a combination thereof. If necessary, a knowntreatment such as a concentration operation, a filtration operation, acentrifugation operation and a drying operation can be performed.

EXAMPLES

Hereinafter, the present embodiment will be described by SynthesisExamples, Examples and Comparative Examples in more detail, but thepresent embodiment is not limited thereto at all.

(Carbon Concentration and Oxygen Concentration)

The carbon concentration and the oxygen concentration (% by mass) weremeasured by organic element analysis using the following apparatus.

Apparatus: CHN CORDER MT-6 (manufactured by Yanaco Bunseki Kogyo Co.)

(Molecular Weight)

The molecular weight was measured by LC-MS (liquid chromatography massspectrometry) analysis using “Acquity UPLC/MALDI-Synapt HDMS”manufactured by Water.

(Molecular Weight in Terms of Polystyrene)

Gel permeation chromatography (GPC) analysis using the followingapparatus and the like was performed to determine the weight averagemolecular weight (Mw) and the number average molecular weight (Mn) interms of polystyrene, and to determine the degree of dispersion (Mw/Mn).

Apparatus: Shodex GPC-101 type (manufactured by Showa Denko K. K.)

Column: KF-80M×3

Eluent: THF 1 mL/min

Temperature: 40° C.

(Thermal Weight Loss Temperature)

An “EXSTAR 6000 DSC” apparatus manufactured by SII NanoTechnology Inc.was used, and about 5 mg of a sample was placed in an unsealed aluminumcontainer and heated to 500° C. at a rate of temperature rise of 10°C./min in a nitrogen gas (30 mL/min) stream. In this time, the 10%thermal weight loss temperature was measured.

(Solubility)

The amount of each compound dissolved in 1-methoxy-2-propanol (PGME) andpropylene glycol monomethyl ether acetate (PGMEA) was measured at 23°C., and the results were each evaluated as the solubility according tothe following criteria.

Evaluation A: 20% by mass or more

Evaluation B: 10% by mass or more and less than 20% by mass

Evaluation C: less than 10% by mass

(Example 1) Synthesis of BiF-I-1

A container having an inner volume of 200 mL, equipped with a stirrer, acondenser and a burette, was prepared. To this container were charged 30g (161 mmol) of 4,4-biphenol (reagent produced by Tokyo ChemicalIndustry Co., Ltd.), 15 g (65 mmol) of 4-iodobenzaldehyde (reagentproduced by Tokyo Chemical Industry Co., Ltd.) and 100 mL of4-butyrolactone, and 3.9 g (21 mmol) of p-toluenesulfonic acid (reagentproduced by Kanto Chemical Co., Inc.) was added thereto to prepare areaction liquid. The reaction liquid was stirred at 90° C. for 3 hoursto perform a reaction. Then, the reaction liquid was concentrated, 50 gof heptane was added thereto to precipitate a reaction product, and theresultant was cooled to room temperature followed by filtration forseparation. A solid obtained by filtration was dried, and thereafterseparated and purified by column chromatography to thereby provide 4.2 gof an objective compound (BiF-I-1) represented by the following formula.Herein, the following peaks were observed by 400 MHz-¹H-NMR, and it wasconfirmed that the compound had a chemical structure of the followingformula.

1H-NMR: (d-DMSO, internal standard TMS)

δ (ppm) 9.4 (4H, O—H), 6.8-7.8 (18H, Ph-H), 6.2 (1H, C—H)

As a result of organic element analysis, the carbon concentration andthe oxygen concentration of the resulting compound (BiF-I-1) were 82.9%and 11.8%, respectively. In addition, the molecular weight of theresulting compound was measured by the above method, and as a result, itwas 586. Furthermore, as a result of thermogravimetric measurement (TG),the 10% thermal weight loss temperature of the resulting compound(BiF-I-1) was 300° C. or higher. Therefore, the compound was evaluatedto have a high heat resistance and be applicable to high-temperaturebaking. In addition, furthermore, as a result of evaluation of thesolubility in PGME and PGMEA, the solubility was 30% by mass or more(Evaluation A) and compound (BiF-I-1) was evaluated to have an excellentsolubility. Therefore, compound (BiF-I-1) was evaluated to have a highstorage stability in a solution state and also be sufficientlyapplicable to an edge bead rinse liquid (mixed liquid of PGME/PGMEA)widely used in a semiconductor microfabrication process.

(Example 2) Synthesis of BiF-I-2

A container having an inner volume of 200 mL, equipped with a stirrer, acondenser and a burette, was prepared. To this container were charged 30g (161 mmol) of 4,4-biphenol (reagent produced by Tokyo ChemicalIndustry Co., Ltd.), 15 g (54 mmol) of 5-iodovanillin (reagent producedby Tokyo Chemical Industry Co., Ltd.) and 100 mL of 4-butyrolactone, and3.9 g (21 mmol) of p-toluenesulfonic acid (reagent produced by KantoChemical Co., Inc.) was added thereto to prepare a reaction liquid. Thereaction liquid was stirred at 90° C. for 3 hours to perform a reaction.Then, the reaction liquid was concentrated, 50 g of heptane was addedthereto to precipitate a reaction product, and the resultant was cooledto room temperature followed by filtration for separation. A solidobtained by filtration was dried, and thereafter separated and purifiedby column chromatography to thereby provide 5.1 g of an objectivecompound (BiF-I-2) represented by the following formula. Herein, thefollowing peaks were observed by 400 MHz-¹H-NMR, and it was confirmedthat the compound had a chemical structure of the following formula.

¹H-NMR: (d-DMSO, internal standard TMS)

δ (ppm) 9.3 (4H, O—H), 6.4-7.3 (16H, Ph-H), 6.1 (1H, C—H)

As a result of organic element analysis, the carbon concentration andthe oxygen concentration of the resulting compound (BiF-I-2) were 82.9%and 11.8%, respectively. In addition, the molecular weight of theresulting compound was measured by the above method, and as a result, itwas 632. Furthermore, as a result of thermogravimetric measurement (TG),the 10% thermal weight loss temperature of the resulting compound(BiF-I-2) was 300° C. or higher. Therefore, the compound was evaluatedto have a high heat resistance and be applicable to high-temperaturebaking. In addition, furthermore, as a result of evaluation of thesolubility in PGME and PGMEA, the solubility was 30% by mass or more(Evaluation A) and compound (BiF-I-2) was evaluated to have an excellentsolubility. Therefore, compound (BiF-1-2) was evaluated to have a highstorage stability in a solution state and also be sufficientlyapplicable to an edge bead rinse liquid (mixed liquid of PGME/PGMEA)widely used in a semiconductor microfabrication process.

(Example 3) Synthesis of BiF-I-3

A container having an inner volume of 200 mL, equipped with a stirrer, acondenser and a burette, was prepared. To this container were charged 30g (161 mmol) of 4,4-biphenol (reagent produced by Tokyo ChemicalIndustry Co., Ltd.), 15 g (65 mmol) of 3-iodobenzaldehyde (reagentproduced by Tokyo Chemical Industry Co., Ltd.) and 100 mL of4-butyrolactone, and 3.9 g (21 mmol) of p-toluenesulfonic acid (reagentproduced by Kanto Chemical Co., Inc.) was added thereto to prepare areaction liquid. The reaction liquid was stirred at 90° C. for 3 hoursto perform a reaction. Then, the reaction liquid was concentrated, 50 gof heptane was added thereto to precipitate a reaction product, and theresultant was cooled to room temperature followed by filtration forseparation. A solid obtained by filtration was dried, and thereafterseparated and purified by column chromatography to thereby provide 4.2 gof an objective compound (BiF-I-3) represented by the following formula.Herein, the following peaks were observed by 400 MHz-¹H-NMR, and it wasconfirmed that the compound had a chemical structure of the followingformula.

¹H-NMR: (d-DMSO, internal standard TMS)

δ (ppm) 9.4 (4H, O—H), 6.5-7.8 (18H, Ph-H), 6.4 (1H, C—H)

As a result of organic element analysis, the carbon concentration andthe oxygen concentration of the resulting compound (BiF-I-3) were 82.9%and 11.8%, respectively. In addition, the molecular weight of theresulting compound was measured by the above method, and as a result, itwas 586. Furthermore, as a result of thermogravimetric measurement (TG),the 10% thermal weight loss temperature of the resulting compound(BiF-I-3) was 300° C. or higher. Therefore, the compound was evaluatedto have a high heat resistance and be applicable to high-temperaturebaking. In addition, furthermore, as a result of evaluation of thesolubility in PGME and PGMEA, the solubility was 30% by mass or more(Evaluation A) and compound (BiF-I-3) was evaluated to have an excellentsolubility. Therefore, compound (BiF-I-3) was evaluated to have a highstorage stability in a solution state and also be sufficientlyapplicable to an edge bead rinse liquid (mixed liquid of PGME/PGMEA)widely used in a semiconductor microfabrication process.

(Example 4) Synthesis of resin (BiFR-I-1)

A four-neck flask having a bottom outlet and an inner volume of 1 L,equipped with a Dimroth condenser, a thermometer and a stirring blade,was prepared. To this four-neck flask were charged 41.0 g (70 mmol,produced by Mitsubishi Gas Chemical Company, Inc.) of BiF-I-1 obtainedin Example 1, 21.0 g (280 mmol as formaldehyde, produced by MitsubishiGas Chemical Company, Inc.) of a 40% by mass aqueous formalin solutionand 0.97 mL of 98% by mass sulfuric acid (produced by Kanto ChemicalCo., Inc.) under a nitrogen stream, and allowed the reaction to rununder ordinary pressure for 7 hours with refluxing at 100° C.Thereafter, 180.0 g of o-xylene (special grade chemical, produced byWako Pure Chemical Industries, Ltd.) as a dilution solvent was added tothe reaction liquid and left to stand, and then an aqueous phase being abottom phase was removed. Furthermore, the resultant was neutralized andwashed with water, and o-xylene was distilled off under reducedpressure, thereby providing 52.2 g of resin (BiFR-I-1) as a brown solid.

With respect to resin (BiFR-I-1) obtained, Mn was 1685, Mw was 3120 andMw/Mn was 1.85. As a result of thermogravimetric measurement (TG), the10% thermal weight loss temperature of resin (BiFR-I-1) obtained was300° C. or higher. Therefore, the resin was evaluated to be applicableto high-temperature baking. As a result of evaluation of the solubilityin PGME and PGMEA, the solubility was 10% by mass or more (Evaluation A)and resin (BiFR-I-1) was evaluated to have an excellent solubility.

(Example 5) Synthesis of Resin (BiFR-I-2)

A four-neck flask having a bottom outlet and an inner volume of 1 L,equipped with a Dimroth condenser, a thermometer and a stirring blade,was prepared. To this four-neck flask were charged 41.0 g (70 mmol,produced by Mitsubishi Gas Chemical Company, Inc.) of BiF-I-1 obtainedin Example 1, 50.9 g (280 mmol, produced by Mitsubishi Gas ChemicalCompany, Inc.) of 4-biphenylaldehyde, 100 mL of anisole (produced byKanto Chemical Co., Inc.) and 10 mL of oxalic acid dihydrate (producedby Kanto Chemical Co., Inc.) under a nitrogen stream, and allowed thereaction to run under ordinary pressure for 7 hours with refluxing at100° C. Thereafter, 180.0 g of ortho-xylene (special grade chemical,produced by Wako Pure Chemical Industries, Ltd.) as a dilution solventwas added to the reaction liquid and left to stand, and then an aqueousphase being a bottom phase was removed. Furthermore, the resultant wasneutralized and washed with water, and the solvent and the unreacted4-biphenylaldehyde in the organic phase were distilled off under reducedpressure, thereby providing 68.2 g of resin (BiFR-I-2) as a brown solid.

With respect to resin (BiFR-I-2) obtained, Mn was 2080, Mw was 3650 andMw/Mn was 1.75. As a result of thermogravimetric measurement (TG), the10% thermal weight loss temperature of resin (BiFR-I-2) obtained was300° C. or higher. Therefore, the resin was evaluated to be applicableto high-temperature baking. As a result of evaluation of the solubilityin PGME and PGMEA, the solubility was 10% by mass or more (Evaluation A)and resin (BiFR-I-2) was evaluated to have an excellent solubility.

Comparative Example 1

A four-neck flask having a bottom outlet and an inner volume of 10 L,equipped with a Dimroth condenser, a thermometer and a stirring bladewas prepared. To this four-neck flask were charged 1.09 kg (7 mol,produced by Mitsubishi Gas Chemical Company, Inc.) of1,5-dimethylnaphthalene, 2.1 kg (28 mol as formaldehyde, produced byMitsubishi Gas Chemical Company, Inc.) of a 40% by mass aqueous formalinsolution and 0.97 mL of 98% by mass sulfuric acid (produced by KantoChemical Co., Inc.) under a nitrogen stream, and allowed the reaction torun under ordinary pressure for 7 hours with refluxing at 100° C.Thereafter, ethylbenzene (special grade chemical, produced by Wako PureChemical Industries, Ltd.) (1.8 kg) as a dilution solvent was added tothe reaction solution and left to stand, and then an aqueous phase beinga bottom phase was removed. Furthermore, the resultant was neutralizedand washed with water, and ethylbenzene and the unreacted1,5-dimethylnaphthalene were distilled off under reduced pressure,thereby providing 1.25 kg of a dimethylnaphthalene formaldehyde resin asa light-brown solid. With respect to the molecular weight of theresulting dimethylnaphthalene formaldehyde, Mn was 562, Mw was 1168 andMw/Mn was 2.08. In addition, the carbon concentration was 84.2% by mass,and the oxygen concentration was 8.3% by mass.

Subsequently, a four-neck flask having an inner volume of 0.5 L,equipped with a Dimroth condenser, a thermometer and a stirring blade,was prepared. To this four-neck flask were charged 100 g (0.51 mol) ofthe dimethylnaphthalene formaldehyde resin obtained as described aboveand 0.05 g of paratoluenesulfonic acid under a nitrogen stream, heatedfor 2 hours with the temperature being raised to 190° C., and thenstirred. Thereafter, 52.0 g (0.36 mol) of 1-naphthol was further addedthereto, and further heated to 220° C. to allow the reaction to run for2 hours. After being diluted with a solvent, the resultant wasneutralized and washed with water, and the solvent was removed underreduced pressure to thereby provide 126.1 g of a modified resin (CR-1)as a blackish brown solid.

With respect to the resulting resin (CR-1), Mn was 885, Mw was 2220 andMw/Mn was 4.17. In addition, the carbon concentration was 89.1% by massand the oxygen concentration was 4.5% by mass. In addition, as a resultof thermogravimetric measurement (TG), the 10% thermal weight losstemperature of the resulting resin (CR-1) was less than 350° C.Therefore, the resin was evaluated to have difficulty in application tohigh-temperature baking where high etching resistance and heatresistance were required. Furthermore, as a result of evaluation of thesolubility in PGME and PGMEA, the solubility was evaluated to be 10% bymass or more and less than 20% by mass (Evaluation B).

Examples 6 to 10 and Comparative Example 2

Each composition for forming an underlayer film for lithography wasprepared so that each composition shown in Table 1 was achieved. Herein,the following materials were used.

Acid generator: di-tert-butyldiphenyliodonium nonafluoromethanesulfonate(DTDPI) produced by Midori Kagaku Co., Ltd.

Crosslinking agent: Nikalac MX270 (Nikalac) produced by Sanwa ChemicalCo., Ltd.

Organic solvent: propylene glycol monomethyl ether acetate acetate(PGMEA) Novolac: PSM4357 produced by Gun Ei Chemical Industry Co., Ltd.

Then, each composition for forming an underlayer film of Examples 1 to 5and Comparative Example 1 was spin-coated on a silicon substrate, andthereafter baked at 240° C. for 60 seconds to prepare each underlayerfilm having a film thickness of 200 nm. An “etching test” was performedunder conditions shown below to perform the following “Evaluation ofetching resistance”. The evaluation results are shown in Table 1.

[Etching Test]

Etching apparatus: RIE-10NR manufactured by Samco Inc.

Output: 50 W

Pressure: 20 Pa

Time: 2 min

Etching gas

Ar gas flow rate: CF₄ gas flow rate: O₂ gas flow rate=50:5:5 (sccm)

[Evaluation of Etching Resistance]

The evaluation of etching resistance was performed according to thefollowing procedure. First, an underlayer film of novolac was preparedunder the same conditions as those in Example 6 except that novolac(PSM4357 produced by Gunei Chemical Industry Co., Ltd.) was used insteadof the compounds (BiF-I-1) used in Example 6. Then, the etching test wasperformed with respect to the underlayer film of novolac as a subject,and the etching rate in that time was measured.

Then, the etching test was performed with respect to each underlayerfilm of Examples 6 to 10 and Comparative Example 2 as a subject, and theetching rate in that time was measured. Then, the etching resistanceswere evaluated according to the following criteria based on the etchingrate of the underlayer film of novolac.

<Evaluation Criteria>

Evaluation A: etching rate of less than −10% compared with the etchingrate of the underlayer film of novolac

Evaluation B: etching rate of −10% or more and +5% or less compared withthe etching rate of the underlayer film of novolac

Evaluation C: etching rate of more than +5% compared with the etchingrate of the underlayer film of novolac

TABLE 1 Material for forming underlayer Acid film Organic generatorCrosslinking Evaluation of (parts by solvent (parts (parts by agent(parts by etching mass) by mass) mass) mass) resistance Example 6BiF-I-1 PGMEA DTDPI Nikalac A (10) (90) (0.5) (0.5) Example 7 BiF-I-2PGMEA DTDPI Nikalac A (10) (90) (0.5) (0.5) Example 8 BiF-I-3 PGMEADTDPI Nikalac A (10) (90) (0.5) (0.5) Example 9 BiFR-I-1 PGMEA DTDPINikalac B (10) (90) (0.5) (0.5) Example 10 BiFR-I-2 PGMEA DTDPI NikalacB (10) (90) (0.5) (0.5) Comparative CR-1 PGMEA DTDPI Nikalac C Example 2(10) (90) (0.5) (0.5)

Example 11

Then, the composition for forming an underlayer film for lithography inExample 6 was coated on a SiO₂ substrate having a film thickness of 300nm, and baked at 240° C. for 60 seconds and further at 400° C. for 120seconds to thereby form an underlayer film having a film thickness of 85nm. A resist solution for ArF was coated on the underlayer film, andbaked at 130° C. for 60 seconds to thereby form a photoresist layerhaving a film thickness of 140 nm. Herein, as the resist solution forArF, one prepared by blending 5 parts by mass of the compound of thefollowing formula (3), 1 part by mass of triphenylsulfoniumnonafluoromethanesulfonate, 2 parts by mass of tributylamine, and 92parts by mass of PGMEA was used.

A compound of the following formula (3) was prepared as follows. Thatis, 4.15 g of 2-methyl-2-methacryloyloxyadamantane, 3.00 g ofmethacryloyloxy-y-butyrolactone, 2.08 g of 3-hydroxy-1-adamantylmethacrylate and 0.38 g of azobisisobutyronitrile were dissolved in 80mL of tetrahydrofuran to provide a reaction solution. This reactionsolution was subjected to polymerization under a nitrogen atmosphere for22 hours with the reaction temperature being kept at 63° C., andthereafter the reaction solution was dropped in 400 mL of n-hexane. Aproduct resin thus obtained was solidified and purified, and a whitepowder produced was taken by filtration and dried under reduced pressureat 40° C. overnight to provide a compound represented by the followingformula.

In the formula (3), the numerals 40, 40, and 20 indicate the proportionsof the respective constituent units, and do not mean a block copolymer.

Then, the photoresist layer was exposed by using an electron beamlithography apparatus (ELS-7500, produced by Elionix, Inc., 50 keV),baked at 115° C. for 90 seconds (PEB), and developed with a 2.38% bymass aqueous tetramethylammonium hydroxide (TMAH) solution for 60seconds, thereby providing a positive-type resist pattern.

Comparative Example 3

Except that no underlayer film was formed, the same manner as in Example11 was performed to form a photoresist layer directly on a SiO₂substrate to provide a positive-type resist pattern.

[Evaluation]

The shapes of the resist patterns of 45 nm L/S (1:1) and 80 nm L/S (1:1)provided in each of Example 11 and Comparative Example 3 were observedby using an electron microscope (S-4800) manufactured by Hitachi Ltd. Acase where the shape of the resist pattern after development had nopattern collapse and had good rectangularity was evaluated to be goodand a case the shape had pattern collapse and did not have goodrectangularity was evaluated to be poor. In the observation results, theminimum line width where there was no pattern collapse andrectangularity was good was defined as the resolution and used as anevaluation index. Furthermore, the minimum amount of electron beamenergy, where a good pattern shape could be drawn, was defined as thesensitivity and used as an evaluation index. The results are shown inTable 2.

TABLE 2 Material Resist pattern for forming Resolution Sensitivityformation after underlayer film (nmL/S) (μC/cm²) development Example 11Material 45 10 Good described in Example 6 Comparative Not used 80 26Not good Example 3

As can be seen from Table 2, it was at least confirmed that theunderlayer film of Example 11 was significantly excellent in both ofresolution and sensitivity as compared with that of Comparative Example3. It was also confirmed that the resist pattern shape after developmenthad no pattern collapse and had good rectangularity. Furthermore, it wasalso confirmed from the difference in the resist pattern shape afterdevelopment that the material for forming an underlayer film forlithography of Example 6 had good adhesiveness with a resist material.

Example 12

The composition for forming an underlayer film for lithography used inExample 6 was coated on a SiO₂ substrate having a film thickness of 300nm, and baked at 240° C. for 60 seconds and further at 400° C. for 120seconds to thereby form an underlayer film having a film thickness of 90nm. A silicon-containing intermediate layer material was coated on theunderlayer film, and baked at 200° C. for 60 seconds to thereby form anintermediate layer film having a film thickness of 35 nm. Furthermore,the resist solution for ArF was coated on the intermediate layer film,and baked at 130° C. for 60 seconds to thereby form a photoresist layerhaving a film thickness of 150 nm. Herein, a silicon atom-containingpolymer obtained as described below was used as the silicon-containingintermediate layer material.

In 200 g of tetrahydrofuran (THF) and 100 g of pure water were dissolved16.6 g of 3-carboxylpropyltrimethoxysilane, 7.9 g ofphenyltrimethoxysilane and 14.4 g of 3-hydroxypropyltrimethoxysilane,the liquid temperature was set at 35° C., 5 g of oxalic acid wasdropped, thereafter the temperature was raised to 80° C., and acondensation reaction of silanol was performed. Next, 200 g of diethylether was added thereto to separate an aqueous layer, an organic liquidlayer was washed with ultrapure water twice, 200 g of propylene glycolmonomethyl ether acetate (PGMEA) was added, and THF and diethylether/water were removed with the liquid temperature being raised to 60°C. under reduced pressure, to provide a silicon atom-containing polymer.

Then, the photoresist layer was exposed with a mask by using an electronbeam lithography apparatus (ELS-7500, produced by Elionix, Inc., 50keV), baked at 115° C. for 90 seconds (PEB), and developed with a 2.38%by mass aqueous tetramethylammonium hydroxide (TMAH) solution for 60seconds, thereby providing a positive-type resist pattern of 45 nm L/S(1:1). Thereafter, RIE-10NR manufactured by Samco Inc. was used toperform dry etching processing of a silicon-containing intermediatelayer film (SOG) with the resulting resist pattern as a mask, andsubsequently, dry etching processing of an underlayer film with theresulting silicon-containing intermediate layer film pattern as a maskand dry etching processing of a SiO₂ film with the resulting underlayerfilm pattern as a mask were sequentially performed.

The respective etching conditions are as shown below.

Etching conditions of resist intermediate layer film with resist pattern

Output: 50 W

Pressure: 20 Pa

Time: 1 min

Etching gas

Ar gas flow rate: CF₄ gas flow rate: O₂ gas flow rate=50:8:2 (sccm)

Etching conditions of resist underlayer film with resist intermediatefilm pattern

Output: 50 W

Pressure: 20 Pa

Time: 2 min

Etching gas

Ar gas flow rate: CF₄ gas flow rate: O₂ gas flow rate=50:5:5 (sccm)

Etching conditions of SiO₂ film with resist underlayer film pattern

Output: 50 W

Pressure: 20 Pa

Time: 2 min

Etching gas

Ar gas flow rate: C₅F₁₂ gas flow rate: C₂F₆ gas flow rate: O2 gas flowrate=50:4:3:1 (sccm)

[Evaluation]

The pattern cross section (shape of SiO₂ film after etching) obtained inExample 12 as described above was observed by using an electronmicroscope (S-4800) manufactured by Hitachi Ltd., and it was thusconfirmed that the SiO₂ film after etching in multilayer resistprocessing had a rectangular shape with no defects showing a good resultwith respect to the underlayer film in each of Examples.

(Example 13) Purification of BiF-I-1

To a four-neck flask (bottom outlet type) having a volume of 1000 mL wascharged 150 g of a solution (10% by mass) in which BiF-I-1 obtained inExample 1 was dissolved in PGMEA, and heated to 80° C. with stirring.Then, 37.5 g of an aqueous oxalic acid solution (pH: 1.3) was addedthereto, stirred for 5 minutes and thereafter left to stand for 30minutes. The resultant was thus separated to an oil phase and an aqueousphase, and therefore the aqueous phase was removed. Such an operationwas repeated once, and thereafter the resulting oil phase was chargedwith 37.5 g of ultrapure water, stirred for 5 minutes and thereafterleft to stand for 30 minutes to remove the aqueous phase. Such anoperation was repeated three times, and thereafter the flask wassubjected to pressure reduction to 200 hPa or less while being heated to80° C., to thereby allow the remaining water content and PGMEA to bedistilled off by concentration. Thereafter, dilution with PGMEA (ELgrade, reagent produced by Kanto Chemical Co., Inc.) was made to adjustthe concentration to 10% by mass, thereby providing a solution ofBiF-I-1 having a reduced metal content, in PGMEA.

The contents of various metals were measured by ICP-MS with respect tothe 10% by mass BiF-I-1 solution in PGMEA before treatment, and thesolutions obtained in Example 13. The measurement results are shown inTable 3.

TABLE 3 Metal content (ppb) Na Mg K Fe Cu Zn Before treatment >9953.4 >99 >99 26.3 23.5 BiF-I-1 Example 13 3.2 1.8 1.5 2.8 0.6 0.8

As described above, the present invention is not intended to be limitedto Examples above, and can be appropriately modified without departingfrom the gist thereof.

The present application is based on Japanese Patent Application(Japanese Patent Application No. 2015-069989) filed with JPO on Mar. 30,2015, the content of which is herein incorporated as reference.

The compound and the resin according to the present invention have arelatively high heat resistance and also a relatively high solventsolubility, and can be applied to a wet process. Therefore, the materialfor forming an underlayer film for lithography and the compositionincluding the material, according to the present invention, can bewidely and effectively utilized in various applications in which theseproperties are required. Therefore, the present invention can be widelyand effectively utilized for, for example, an electric insulatingmaterial; a resist resin; a sealing resin for a semiconductor; anadhesive for a printed wiring board; an electric laminated board mountedon electrical equipment, electronic equipment, industrial equipment andthe like; a matrix resin for a prepreg mounted on electrical equipment,electronic equipment, industrial equipment and the like; a material fora build-up laminated board; a resin for fiber-reinforced plastics; asealing resin for a liquid crystal display panel; a paint; variouscoating agents; an adhesive; a coating agent for a semiconductor; aresist resin for a semiconductor; and a resin for forming an underlayerfilm. In particular, the present invention can be particularlyeffectively utilized in the field of an underlayer film for lithographyand an underlayer film for a multilayer resist according to the presentinvention.

1. A compound represented by following formula (1),

wherein R¹ represents a 2n-valent group having 1 to 30 carbon atoms,each of R² to R⁵ independently represents a straight, branched or cyclicalkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxygroup having 1 to 30 carbon atoms, a halogen atom, a thiol group or ahydroxyl group, provided that at least one selected from R¹ to R⁵represents a group including an iodine atom and at least one R⁴ and/orat least one R⁵ represent/represents one or more selected from the groupconsisting of a hydroxyl group and a thiol group, each of m² and m³independently represents an integer of 0 to 8, each of m⁴ and m⁵independently represents an integer of 0 to 9, provided that m⁴ and m⁵do not represent 0 at the same time, n represents an integer of 1 to 4,and each of p² to p⁵ independently represents an integer of 0 to
 2. 2.The compound according to claim 1, wherein, in the formula (1), at leastone R² and/or at least one R³ represent/represents one or more selectedfrom the group consisting of a hydroxyl group and a thiol group.
 3. Thecompound according to claim 1, wherein the compound represented by theformula (1) is a compound represented by following formula (1a),

wherein R¹ to R⁵ and n are the same as defined in the formula (1), eachof m^(2′) and m^(3′) independently represents an integer of 0 to 4, andeach of m^(4′) and m^(5′) independently represents an integer of 0 to 5,provided that m^(4′) and m^(5′) do not represent 0 at the same time. 4.The compound according to claim 3, wherein the compound represented bythe formula (1a) is a compound represented by following formula (1b),

wherein R¹ is the same as defined in the formula (1), each of R⁶ and R⁷independently represents a straight, branched or cyclic alkyl grouphaving 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms,an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1to 30 carbon atoms, a halogen atom or a thiol group, provided that atleast one selected from R¹, R⁶ and R⁷ represents a group including aniodine atom, and each of m⁶ and m⁷ independently represents an integerof 0 to
 7. 5. The compound according to claim 4, wherein the compoundrepresented by the formula (1b) is a compound represented by followingformula (1c),

wherein each R⁸ independently represents a hydrogen atom, a cyano group,a nitro group, a heterocyclic group, a halogen atom, a straightaliphatic hydrocarbon group having 1 to 20 carbon atoms, a branchedaliphatic hydrocarbon group having 3 to 20 carbon atoms, a cyclicaliphatic hydrocarbon group having 3 to 20 carbon atoms, an aryl grouphaving 6 to 20 carbon atoms, an alkenyl group having 2 to 10 carbonatoms, an alkoxy group having 1 to 30 carbon atoms, a thiol group or ahydroxyl group, provided that at least one R⁸ represents a groupincluding an iodine atom.
 6. The compound according to claim 5, whereinthe compound represented by the formula (1c) is a compound representedby following formula (1d),

wherein each R⁹ independently represents a cyano group, a nitro group, aheterocyclic group, a halogen atom, a straight aliphatic hydrocarbongroup having 1 to 20 carbon atoms, a branched aliphatic hydrocarbongroup having 3 to 20 carbon atoms, a cyclic aliphatic hydrocarbon grouphaving 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms,an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1to 30 carbon atoms, a thiol group or a hydroxyl group, and m⁹ representsan integer of 0 to
 4. 7. A resin obtained with the compound according toclaim 1 as a monomer.
 8. The resin according to claim 7, wherein theresin is obtained by reacting the compound with a compound havingcrosslinking reactivity.
 9. The resin according to claim 8, wherein thecompound having crosslinking reactivity is an aldehyde, a ketone, acarboxylic acid, a carboxylic halide, a halogen-containing compound, anamino compound, an imino compound, an isocyanate or an unsaturatedhydrocarbon group-containing compound.
 10. A resin having a followingstructure represented by formula (2),

wherein R¹ represents a 2n-valent group having 1 to 30 carbon atoms,each of R² to R⁵ independently represents a straight, branched or cyclicalkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxygroup having 1 to 30 carbon atoms, a halogen atom, a thiol group or ahydroxyl group, provided that at least one selected from R¹ to R⁵represents a group including an iodine atom and at least one R⁴ and/orat least one R⁵ represent/represents one or more selected from ahydroxyl group and a thiol group, L represents a straight or branchedalkylene group having 1 to 20 carbon atoms, or a single bond, each of m²and m³ independently represents an integer of 0 to 8, each of m⁴ and m⁵independently represents an integer of 0 to 9, provided that m⁴ and m⁵do not represent 0 at the same time, n represents an integer of 1 to 4,and each of p² to p⁵ independently represents an integer of 0 to
 2. 11.A material for forming an underlayer film for lithography, comprisingthe compound according to claim
 1. 12. A composition for forming anunderlayer film for lithography, comprising the material for forming theunderlayer film for lithography according to claim 11, and a solvent.13. The composition for forming the underlayer film for lithographyaccording to claim 12, further comprising an acid generator.
 14. Thecomposition for forming the underlayer film for lithography according toclaim 12, further comprising a crosslinking agent.
 15. An underlayerfilm for lithography, wherein the underlayer film is formed from thecomposition for forming the underlayer film for lithography according toclaim
 12. 16. A resist pattern forming method, comprising a step offorming an underlayer film on a substrate by using the composition forforming the underlayer film according to claim 12, a step of forming atleast one photoresist layer on the underlayer film, and a step ofirradiating a predetermined region of the photoresist layer withradiation, and developing it.
 17. A circuit pattern forming method,comprising a step of forming an underlayer film on a substrate by usingthe composition for forming the underlayer film according to claim 12, astep of forming an intermediate layer film on the underlayer film byusing a silicon atom-containing resist intermediate layer film material,a step of forming at least one photoresist layer on the intermediatelayer film, a step of irradiating a predetermined region of thephotoresist layer with radiation, to form a developed resist pattern, astep of etching the intermediate layer film with the resist pattern as amask, to form an intermediate layer film pattern, a step of etching theunderlayer film with the intermediate layer film pattern as an etchingmask, to form an underlayer film pattern, and a step of etching thesubstrate with the underlayer film pattern as an etching mask, to form asubstrate pattern.
 18. A purification method of a compound or a resin,comprising a step of bringing a solution including the compoundaccording to claim 1 or a resin obtained with the compound as a monomer,and an organic solvent optionally immiscible with water into contactwith an acidic aqueous solution, to thereby extract the compound or theresin.
 19. The purification method according to claim 18, wherein theacidic aqueous solution is an aqueous solution of at least one mineralacid selected from the group consisting of hydrochloric acid, sulfuricacid, nitric acid and phosphoric acid, or an aqueous solution of atleast one organic acid selected from the group consisting of aceticacid, propionic acid, oxalic acid, malonic acid, succinic acid, fumaricacid, maleic acid, tartaric acid, citric acid, methanesulfonic acid,phenolsulfonic acid, p-toluenesulfonic acid and trifluoroacetic acid.20. The purification method according to claim 18, wherein the organicsolvent optionally immiscible with water is toluene, 2-heptanone,cyclohexanone, cyclopentanone, methyl isobutyl ketone, propylene glycolmonomethyl ether acetate or ethyl acetate.
 21. The purification methodaccording to claim 18, further comprising a step of extracting thecompound or the resin with water, after the extraction step.
 22. Amaterial for forming an underlayer film for lithography, comprising theresin according to claim 7.